Monthly Archives: October 2012

A Height Increase Journal To Write Down My Research Notes

One thing I have been doing is getting a journal so I can write down notes from the research I’ve been doing. So far I have kept track of

1. Different types of growth factors on chondrogenesis and osteogenesis.

2. The dimensions and values of the mechanical and material properties of the bone in every single area.

3. The protein/hormone signaling pathway map.

4. Food and supplements which have known height increasing properties.

5. Major genes that are involved in endochondral ossification .

6. Anatomy figures of the muscles and ligaments around the bone.

How Platelet Derived Growth Factor PDGF Effects Growth And Height

Another type of growth factor which I have been noticing being mentioned a lot when looking at the regulation of the growth plate have been a group of growth factors known as Platelet Derived Growth Factor, PDGF. This post will be my attempt in doing at least some basic research on this group of growth regulation proteins. I hope that I will be able to find at least a few from the overall group that do have a critical role in growth plate regulation and chondrocyte proliferation.

First, let’s start with Wikipedia and see what it has to say about Platelet Derived Growth Factors, PDGFs….

In molecular biology, platelet-derived growth factor (PDGF) is one of the numerous growth factors, or proteins that regulate cell growth and division. In particular, it plays a significant role in blood vessel formation (angiogenesis), the growth of blood vessels from already-existing blood vessel tissue. Uncontrolled angiogenesis is a characteristic of cancer.

PDGF is a potent mitogen for cells of mesenchymal origin, including smooth muscle cells and glial cells.

Though it is synthesized stored and released by platelets upon activation, it is produced by a plethora of cells including smooth muscle cells, activated macrophages, and endothelial cells

Function

PDGFs are mitogenic during early developmental stages, driving the proliferation of undifferentiated mesenchyme and some progenitor populations. During later maturation stages, PDGF signalling has been implicated in tissue remodelling and cellular differentiation, and in inductive events involved in patterning and morphogenesis. In addition to driving mesenchymal proliferation, PDGFs have been shown to direct the migration, differentiation and function of a variety of specialised mesenchymal and migratory cell types, both during development and in the adult animal.

PDGF plays a role in embryonic development, cell proliferation, cell migration, and angiogenesis. PDGF has also been linked to several diseases such as atherosclerosis, fibrosis and malignant diseases.

PDGF is also known to maintain proliferation of oligodendrocyte progenitor cells.

Analysis & Interpretation:

From this quick definition found from Wikipedia, I would guess that the PDGFs are a group of proteins that regulate the rate at which many progenitor cells divide. The PDGF is known as a mitogen. From Wikipedia, the term mitogen refers to some external factor or compound that causes a cell to start dividing aka proliferating. If this function was applied to the focus of our research, height increase, we could say that there should be some type of mitogen, probably a PDGF that is also involved in controlling the rate at which the chondrocytes in the growth plate will divide and grow in number. The undifferentiated mesenchyme the definition is talking about can refer to the MSCs we find in the bone marrow of the intermedullary cavity of long bones.

However it seems that the PDGFs seem to work mainly on smooth muscle cells, glial cells, and oligodendrocyte progenitor cells (or a type of brain cell). What may be the most important thing to take out of this article is that the PDGFs are involved in the formation of blood vessels aka angiogenesis.

For the purposes of our desire to increase height, previous research has shown that having blood vessel disruption in the metaphyseal area of long bones may actually increase longtitudinal growth. It is important to realize that a long bone in a human body has blood vessels going in various parts of the long bone, to the ends of the bone, the epiphysis, to the middle, and to the growth plates as well.

Let’s not forget that the growth plates are cartilage, and cartilage intrinsically does not have any blood vessels going through the extracellular matric of the cartilage. The cartilage is both protected from angiogenesis and vascularization by the perichondrium (in the articular and epiphyseal cartilage) as well as angiogenesis inhibitor factors like Chondromodulin. Any “food” that the chondrocytes in the epiphyseal cartilage does get must be diffused through the matrix to it. As it should happen, when the growth plates starts getting punctured in the walls by the blood vessels, that is when the rate at which ossification and calcification of the cartilage become increased beyond the limit at which the cartilage can possibly regenerate more chondrocytes which form cartilage from the resting zone.

If we now look at the Wikipedia article on Platelet Derived Growth Factor Receptor…

Platelet-derived growth factor receptors (PDGF-R) are cell surface tyrosine kinase receptors for members of the platelet-derived growth factor (PDGF) family. PDGF subunits -A and -B are important factors regulating cell proliferation, cellular differentiation, cell growth, development and many diseases including cancer. There are two forms of the PDGF-R, alpha and beta each encoded by a different gene. Depending on which growth factor is bound, PDGF-R homo- or heterodimerizes.

Interaction with signal transduction molecules

Tyrosine phosphorylation sites in growth factor receptors serve two major purposes: to control the state of activity of the kinase and to create binding sites for downstream signal transduction molecules, which in many cases also are substrates for the kinase.

Analysis & Interpretation:

We are seeing that the PDGF receptors are just like so many other receptors we have been studying and research before. They are also tyrosine kinase, which we had studied when we looked at the Wnt/Beta-Catenin Signaling pathway and the PI3K/AKT/mTOR signaling pathway. The PDGFs are just another type of growth factor then that “moves” in the extracellular fluid to eventually bind with the receptors it has on the outer cellular membrane which it would cause a cascading signal pathway. However, this type of knowledge does not tell us how exactly do this type of growth factor affect and relate to growth and overal human height.

Thus, we need to turn to studies which we might be able to find from PubMed. The first study I will turn to is “Platelet derived growth factor stimulates chondrocyte proliferation but prevents endochondral maturation.”

Endocrine. 1997 Jun;6(3):257-64.

Platelet derived growth factor stimulates chondrocyte proliferation but prevents endochondral maturation.

Kieswetter K, Schwartz Z, Alderete M, Dean DD, Boyan BD.
Source
OsteoBiologics, Inc., San Antonio, TX, USA.

Abstract

Platelet-derived growth factor (PDGF) is a cytokine released by platelets at sites of injury to promote mesenchymal cell proliferation. Since many bone wounds heal by endochondral bone formation, we examined the response of chondrocytes in the endochondral lineage to PDGF. Confluent cultures of rat costochondral resting zone cartilage cells were incubated with 0-300 ng/mL PDGF-BB for 24 h to determine whether dose-dependent changes in cell proliferation (cell number and [3H]-thymidine incorporation), alkaline phosphatase specific activity, [35S]-sulfate incorporation, or [3H]-proline incorporation into collagenase-digestible protein (CDP) or noncollagenase-digestible protein (NCP), could be observed. Long-term effects of PDGF were assessed in confluent cultures treated for 1, 2, 4, 6, 8, or 10 d with 37.5 or 150 ng/mL PDGF-BB. To determine whether PDGF-BB could induce resting zone chondrocytes to change maturation state to a growth zone chondrocyte phenotype, confluent resting zone cell cultures were treated for 1, 2, 3, or 5 d with 37.5 or 150 ng/ml PDGF-BB and then challenged for an additional 24 h with 1,25-(OH)2D3. PDGF-BB caused a dose-dependent increase in cell number and [3H]-thymidine incorporation at 24 h. The proliferative effect of the cytokine decreased with time. PDGF-BB had no effect on alkaline phosphatase at 24 h, but at later times, the cytokine prevented the normal increase in enzyme activity seen in post-confluent cultures. This effect was primarily on the cells and not on the matrix. PDGF-BB stimulated [35S]-sulfate incorporation at all times examined, but had no effect on [3H]-proline incorporation into either the CDP or NCP pools. Thus, percent collagen production was not changed. Treatment of the cells for up to 5 d with PDGF-BB failed to elicit a 1,25-(OH)2D3 responsive phenotype typical of rat costochondral growth zone cartilage cells. These results show that committed chondrocytes can respond to PDGF-BB with increased proliferation. The effect of the cytokine is to enhance cartilage matrix production, but at the same time to prevent progression of the cells along the endochondral maturation pathway.

PMID: 936868[PubMed – indexed for MEDLINE]

Analysis & Interpretation:

From Wikipedia…

Cytokines are small cell-signaling protein molecules that are secreted by numerous cells and are a category of signaling molecules used extensively in intercellular communication. Cytokines can be classified as proteins, peptides, or glycoproteins; the term “cytokine” encompasses a large and diverse family of regulators produced throughout the body by cells of diverse embryological origin. The term “cytokine” has been used to refer to the immuno modulating agents, such as interleukins and interferons. Biochemists disagree as to which molecules should be termed cytokines and which hormones.

Platelets, or thrombocytes are small, irregularly shaped clear cell fragments (i.e. cells that do not have a nucleus) which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days. Platelets are a natural source of growth factors.

We learn that many wounds, which I would guess represent both skin lacerations and bone fractures, when going through the process of healing have these platelets which release the PDGF, also known as a cytokine. The researchers would take resting zone chondrocytes from the costochondral region and have them cultured and have a specific type of PDGF called PDGF-BB added to see whether the cultures will show proliferation, increased collagen production, alkaline phosphatase activity, thymidine incorporation, or  sulfate or proline incorporation. The results showed that with the PDGF-BB it seems that the initial injections did show the resting zone chondrocytes proliferate (ie. grow in number and show thymidine incorporation) but the effects over time of the PDGF decreased in effectiveness.

From 2nd PubMed study…

[Degree of differentiation of chondrocytes and their pretreatment with platelet-derived-growth factor. Regulating induction of cartilage formation in resorbable tissue carriers in vivo].

Orthopade. 2000 Feb;29(2):120-8.

[Article in German]

Lohmann CH, Schwartz Z, Niederauer GG, Boyan BD.

Source

Department of Orthopaedics, University of Texas Health Science Center, San Antonio, USA. LohmannCH@t-online.de

Abstract

Current methods for articular cartilage repair are unpredictable with respect to clinical success. In the present study, we investigated the ability of cells from articular cartilage, perichondrium, and costochondral resting zone to form new cartilage when loaded onto biodegradable scaffolds and implanted into calf muscle pouches of nu/nu mice. Prior in vitro studies showed that platelet derived growth factor-BB (PDGF-BB), but not transforming growth factor beta-1 (TGF-beta 1), basic fibroblast growth factor, or bone morphogenetic protein-2 promoted proliferation and extracellular matrix sulfation of resting zone chondrocytes without causing the cells to exhibit a hypertrophic chondrocyte phenotype. TGF-beta 1 has also been shown to stimulate chondrogenesis by multipotent chondroprogenitor cells like those in the perichondrium. In addition, PDGF-BB has been shown to modulate chondrogensis by resting zone cells implanted in poly(D,L-lactide-co-glycolide) (PLG) scaffolds. In the present study we examined whether the cartilage formation is dependent on state of chondrocyte maturation and whether the pretreatment of chondrocytes with growth factors has an influence on the cartilage formation. Scaffolds were manufactured from 80% PLG with a 75:25 lactide:glycolide ratio and 20% modified PLG with a 50:50 lactide:glycolide ratio (PLG-H scaffolds). For each experimental group, four nude mice received two identical implants, one in each calf muscle resulting in an N = 8 implants: PLG-H scaffolds alone; PLG-H scaffolds with cells derived from either the femoral articular cartilage, costochondral periochondrium, or costochondral resting zone cartilage of 125 g male Sprague-Dawley rats; PLG-H scaffolds with either articular chondrocytes or resting zone chondrocytes that were pretreated with 37.5 ng/ml rhPDGF-BB for 4 h or 24 h before implantation, or with perichondrial cells treated with PDGF-BB plus 0.22 ng/ml rhTGF beta-1 for 4 h and 24 h. At 4 or 8 weeks after implantation, samples were harvested and analyzed histomorphometrically for new cartilage formed, area of residual implant and area of fibrous connective tissue. Only resting zone cells showed the ability to form new cartilage at a heterotopic site in this study. There was no neocartilage found in nude mice with implants loaded with either articular chondrocytes or perichondrial cells. Pretreatment of resting zone chondrocytes for 4 h prior to implantation significantly increased the amount of newly formed cartilage after 8 weeks and suppressed chondrocyte hypertrophy. The amount of fibrous connective tissue around implants containing either articular chondrocytes or perichondrial cells decreased with time, whereas the amount of fibrous connective tissue around implants containing resting zone chondrocytes pretreated with PDGF-BB was increased. The results showed that resting zone cells can be successfully incorporated into biodegradable porous PLG scaffolds and can induce new cartilage formation in a nonweight-bearing site. Articular chondrocytes as well as perichondrial cells did not have the capacity for neochondrogenesis when implanted heterotopically in this model.

PMID: 10743633 [PubMed – indexed for MEDLINE]

Analysis & Interpretation:

The researchers wanted to see whether adding a certain type of growth factor into the chondrocytes which was extracted from perichondrium, resting zones, and articular cartilage and then imbedded into scafolds would result in better/ greater cartilage formation. From old results seen from other experiments on the effects of all the most well known growth factors, the TGF-Betas, the BMP-2, the bFGFs, and the PDGFs, the PDGFs seemed to be the group which could get the chondrocytes to proliferate and increase extracellular matrix sulfation without getting the chondrocytes to take the direction of mutaration into hypertrophy. The study was also going to see whether the state of the maturation of the cartilage in the scaffold would also be modulating the cartilage formation rate.

The idea was to take the PGL derived scaffold with chondrocytes embedded into them and implant the scaffold into the limbs of test animals with a growth factor treatment to see whether the growth factor which the scaffold was pretreated with will help in making new cartilage formationBesides using the PDGF-BB as the growth factor, TGF-Beta was also using as a comparison growth factor, as well as combining the two growth factors together. The results reveal that the only type of chondrocytes which showed cartilage formation were from the resting zone. The implants into the mice which were from the articular cartilage or the perichondrium showed no cartilage formation after the implantation of the scaffold/chondrocyte mix. .

Study #3: Formation of repaired hyaline cartilage using PDGF-treated chondrocyte/PCL construct in rabbit knee articular cartilage defect

From the Abstract…

Platelet derived growth factor (PDGF) has a positive mitogenic and chemotactic effect on mesenchyme derived cells, and its receptor has been identified also on chondrocytes [16]. The main reason for the usage of PDGF as a promoting factor for cartilage repair comes from the healing response in cartilage defects treated with microfracture. In this method, the formed clot in the defect site can provide an environment enriched with growth factors such as PDGF, exerting chemotactic and mitogenic effects [17]. PDGF has a direct effect on chondrocytes proliferation, differentiation and cartilage proteoglycan production and is thus believed to be able of enhancing tissue regeneration and repair [15, 16].

Although there are differences between human and animal tissues, for examining a novel treatment, a suitable animal model can be used as an important tool in enhancement of regenerative medicine. Furthermore, histological assessment of human articular cartilage after ACT is limited because biopsy for obtaining specimen may result in joint injury. In this study, we used rabbit which is a widely used animal model in study of tissue regeneration. Regarding the importance of PDGF as promoting factor for cartilage healing, we designed this study to evaluate whether PDGF is able to stimulate transplanted constructs for producing a hyaline-like repaired tissue instead of fibrocartilage one and enhance the integration of chondrocyte/PCL complex implanted in the damaged knee articular cartilage in rabbits.

Analysis & Interpretation:

It would seem that besides the many receptors found on the surface of chondrocytes, the receptor for the Platelet derived growth factor is also on it. It seems that cartilage defects from microfractures show really good results when treated with the PDGF. The interesting thing is that the abstract states explictly that the PDGF has a direct effect on chondrocyte proliferation, differentiation, and proteoglycan production. The most interesting thing that the PDGF has an effect on is that if one uses this type of growth factor on cartilage defects, the cartilage that it can produce is of the hyaline cartilage variety, not he fibrocartilage one would find. As always, the chondrocyte with the PCL scaffold matrix is used for embedding into the damaged region of cartilage in test animals/rabbits.

Short Male Babies And Adult Have Increase Risk Of Violent Suicide Attempts

Me: I found this study which linked to small babies to adult suicide rates to be very interesting. The biological answer that is stated is over the fact that smaller babies haveve less serotonin, which contributes to impulsivity, agression, and suicidal behavior. It seems babies which are born either shorter or lighter than their counter parts are both at risk to suicide. However, that is not all. Short stature in adulthood also increased the suicide tendency, which makes perfect sense, where they were smaller as a baby or average as a baby. It seems no matter how we view it, smaller people just have higher rates of suicide attempts. Obviously there is a social and emotional challenge associated with small stature and I believe completely that anyone who has insecurities with their small stature should seek comfort and help from someone to reduce the risks of suicidal behavior.

From Science Daily…

Short Male Babies Have More Than Double The Risk Of Violent Suicide Attempts, Study Suggests

ScienceDaily (Jan. 18, 2008) — Short male babies run more than double the risk of a violent suicide attempt as an adult, suggests a new study. Catch up growth during childhood does not lessen the impact of short stature at birth, the research shows.

(Me: That is very interesting that catch-up growth seems to have no effect so it is more than just social or emotional but biological in nature)

The findings are based on almost 320,000 Swedish men out of a total of more than 713,000 people all born between 1973 and 1980. Using national registers, they were tracked from birth to the date of attempted suicide, death, emigration, or the end of 1999, whichever came first.

Short babies of less than 47 cm in length, were more likely to attempt suicide as adults, no matter what height they reached in adulthood, compared with normal length babies. Short birth length also more than doubled the risk of a violent suicide attempt as opposed to a non-violent one.

A violent suicide attempt was defined as hanging, the use of a firearm or knives, jumping from a height or in front of vehicles, and drowning.

Short stature in adulthood also boosted the risk.

Men who were normal length babies, but who were short in adult life were 56% more likely than tall men to attempt to take their own lives. The taller a man was, the less likely he was to attempt suicide, the findings showed.

Men who were born underweight (under 2500 g), but who reached normal height were more than 2.5 times as likely to make a violent suicide attempt.

And those who were born prematurely, and therefore short and underweight, were more than four times as likely to attempt violent suicide as those born after 38 to 40 weeks of pregnancy.

The authors suggest that the brain chemical serotonin may be key. It is crucial to brain development and low levels are important in impulsivity, aggression, and suicidal behaviour. Serotonin levels may be affected by premature birth and other factors restricting growth in the womb, they add.

This study, Fetal and childhood growth and the risk of violent and non-violent suicide attempts: A cohort study of 318,953 men, is published in the Journal of Epidemiology and Community Health.

The LIN28B Gene’s Influence On Height

Me: This is news to me since I haven’t read up on the entire list of 180 genes that affect height in the gene database section. I know that Tyler has talked about LIN28B along with HMGA2. It turns out that the LIB28B gene is actually really influential. It mediates the progenitor cells from bone marrow. Note that the article says that LIN28B is associated with timing of menarche (menarche is the time when a female experiences her first period) so it basically tells the body when to start puberty. From study 2 found below, we can see that in an independent study of over 4,000 women if the major allele of LIN28B is expressed, the menarche occurs earlier by at least 0.1 years, which results in earlier puberty, which leads to eventual less adult height. The ScienceDaily article is based on study 3 found below. The SNP testing of the region around the LIN28B shows it correlated to the timing of growth spurts.

From Science Daily….

Growth Curve Analyses of Finnish Population Shed Light On the Genetic Regulation of Growth in Height

ScienceDaily (Apr. 15, 2010) — Researchers at the University of Helsinki and the Institute for Molecular Medicine Finland (FIMM) have shown that a gene called LIN28B strongly influences height growth from birth to adulthood in a complex and sex-spesific manner.

Human growth in height is a multifaceted process including periods of accelerated and decelerated growth velocities. The postnatal growth trajectory can be conceptualized as consisting of three partially overlapping phases: infant growth characterized by rapidly declining growth velocities, slowly decelerating childhood growth, and the pubertal height growth spurt.

Height is strongly regulated by genes, and so far more than 40 genes have been implicated influencing adult height. Yet, little is known about how individual genes regulate growth in height.

Utilizing the unique resource of longitudinal childhood height growth data available in Finnish population cohorts, researchers at the University of Helsinki and the Institute for Molecular Medicine Finland (FIMM) have pinpointed broad height growth regulating effects to a gene called LIN28B. The same gene is known to be a key regulator of developmental timing in the nematode C. elegans and has previously been associated both with timing of menarche and adult height in humans.

Applying genome-wide association mapping technology, the researchers have now shown that the gene strongly influences the timing of the pubertal height growth spurt both in males and females but they also found that it regulates height growth from birth to adulthood in a complex and sex-specific manner.

“Interestingly; two separate variants of the gene were found to influence growth, one with a more prominent height increasing effect in males and another one increasing height only in females,” tells Academy Research Fellow, Dr. Elisabeth Widén.

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Journal Reference:

  1. Elisabeth Widén , Samuli Ripatti , Diana L. Cousminer , Ida Surakka , Tuuli Lappalainen , Marjo-Riitta Järvelin , Johan G. Eriksson , Olli Raitakari , Veikko Salomaa , Ulla Sovio , Anna-Liisa Hartikainen , Anneli Pouta , Mark I. McCarthy , Clive Osmond , Eero Kajantie , Terho Lehtimäki , Jorma Viikari , Mika Kähönen , Chris Tyler-Smith , Nelson Freimer , Joel N. Hirschhorn , Leena Peltonen and Aarno Palotie.Distinct Variants at LIN28B Influence Growth in Height from Birth to Adulthood. American Journal of Human Genetics, 2010; DOI: 10.1016/j.ajhg.2010.03.010
From Nature.com (study 2) HERE…

Nature Genetics 41, 729 – 733 (2009)
Published online: 17 May 2009 | doi:10.1038/ng.382

Genetic variation in LIN28B is associated with the timing of puberty

Ken K Ong1,2,3, Cathy E Elks1,2, Shengxu Li1,2, Jing Hua Zhao1,2, Jian’an Luan1,2, Lars B Andersen4, Sheila A Bingham5,6, Soren Brage1,2, George Davey Smith7, Ulf Ekelund1,2,8, Christopher J Gillson1,2, Beate Glaser7, Jean Golding9, Rebecca Hardy10, Kay-Tee Khaw11, Diana Kuh10, Robert Luben11, Michele Marcus12,13,14, Michael A McGeehin12, Andrew R Ness15, Kate Northstone16, Susan M Ring16, Carol Rubin12, Matthew A Sims1,2, Kijoung Song17, David P Strachan18, Peter Vollenweider19, Gerard Waeber19, Dawn M Waterworth17, Andrew Wong10, Panagiotis Deloukas20, Inês Barroso20, Vincent Mooser17, Ruth J Loos1,2 & Nicholas J Wareham1,2

The timing of puberty is highly variable1. We carried out a genome-wide association study for age at menarche in 4,714 women and report an association in LIN28B on chromosome 6 (rs314276, minor allele frequency (MAF) = 0.33, P = 1.5 × 10−8). In independent replication studies in 16,373 women, each major allele was associated with 0.12 years earlier menarche (95% CI = 0.08–0.16;P = 2.8 × 10−10; combined P = 3.6 × 10−16). This allele was also associated with earlier breast development in girls (P = 0.001; N = 4,271); earlier voice breaking (P = 0.006, N = 1,026) and more advanced pubic hair development in boys (P = 0.01; N = 4,588); a faster tempo of height growth in girls (P = 0.00008; N = 4,271) and boys (P = 0.03; N = 4,588); and shorter adult height in women (P = 3.6 × 10−7; N = 17,274) and men (P = 0.006; N = 9,840) in keeping with earlier growth cessation. These studies identify variation in LIN28B, a potent and specific regulator of microRNA processing2, as the first genetic determinant regulating the timing of human pubertal growth and development.

From PubMed study 2 link HERE…

Am J Hum Genet. 2010 May 14;86(5):773-82. Epub 2010 Apr 15.

Distinct variants at LIN28B influence growth in height from birth to adulthood.

Widén E, Ripatti S, Cousminer DL, Surakka I, Lappalainen T, Järvelin MR, Eriksson JG, Raitakari O, Salomaa V, Sovio U, Hartikainen AL, Pouta A, McCarthy MI,Osmond C, Kajantie E, Lehtimäki T, Viikari J, Kähönen M, Tyler-Smith C, Freimer N, Hirschhorn JN, Peltonen L, Palotie A.

Source

Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland. elisabeth.widen@helsinki.fi

Abstract

We have studied the largely unknown genetic underpinnings of height growth by using a unique resource of longitudinal childhood height data available in Finnish population cohorts. After applying GWAS mapping of potential genes influencing pubertal height growth followed by further characterization of the genetic effects on complete postnatal growth trajectories, we have identified strong association between variants near LIN28B and pubertal growth (rs7759938; female p = 4.0 x 10(-9), male p = 1.5 x 10(-4), combined p = 5.0 x 10(-11), n = 5038). Analysis of growth during early puberty confirmed an effect on the timing of the growth spurt. Correlated SNPs have previously been implicated as influencing both adult stature and age at menarche, the same alleles associating with taller height and later age of menarche in other studies as with later pubertal growth here. Additionally, a partially correlated LIN28B SNP, rs314277, has been associated previously with final height. Testing both rs7759938 and rs314277 (pairwise r(2) = 0.29) for independent effects on postnatal growth in 8903 subjects indicated that the pubertal timing-associated marker rs7759938 affects prepubertal growth in females (p = 7 x 10(-5)) and final height in males (p = 5 x 10(-4)), whereas rs314277 has sex-specific effects on growth (p for interaction = 0.005) that were distinct from those observed at rs7759938. In conclusion, partially correlated variants at LIN28B tag distinctive, complex, and sex-specific height-growth-regulating effects, influencing the entire period of postnatal growth. These findings imply a critical role for LIN28B in the regulation of human growth.

Copyright (c) 2010 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

PMID: 20398887        [PubMed – indexed for MEDLINE] 
PMCID:    PMC2869010

Using Dexamethasone And TGF-Beta1 To Turn Bone Marrow Derived Mesenchymal Progenitor Cells Into Chondrocytes

Me: What this study has shown is another method to turn bone marrow derived mesenchymal progenitor cells. Remember, this is not for adiposed derived adult stem cells, but bone marrow drived mesenchymal progenitor cells. There is a difference, and if I do try to use growth factor combinations to induce height increase, we have to know how the process should happen. This study involved trying out the two growth factors dexamethasone and TGF-Beta1. With the deaxamethasone we are seeing some developed of chondrogenesis as well as collagen type II formation. With time, the type II turns into type X from the obvious differentiation of the chondrocytes into hypertrophic in nature. Besides just using the dexamethasone some TGF-Beta 1 was also added which resulted in call cell culture samples undergoing chondrogenesis. There is an increase in the alkaline phosphatase activity. there is evidence for collagen type II a and type II b and type X. interestingly, type I collagen mRNA is no longer detected.

What this implies: In three of the most recent posts I have looked at the effectiveness of using TGF-1, BMP-3, Dexamethasone, and Chitosan. You can encapsulate the BMP-6, TGF-Beta 1 with Chitosan, and the TGF-Beta 1 with dexamethasone. We are finding like from other studies that the TGF-1 (or TGF-2) works very well with other types of chondroinductive material. I would suggest than first just sending in the TGF-1 with chitosan, then add in the deaxamethasone, and then the BMP-6. It would be interesting to see what would be the result if we tried to multiply the chondrogenetic qualities of all of these growth factors together. With the dexamethasone we should be able to add this into the epiphysis and not just the bone marrow.

From PubMed study link HERE…

Exp Cell Res. 1998 Jan 10;238(1):265-72.

In vitro chondrogenesis of bone marrow-derived mesenchymal progenitor cells.

Johnstone B, Hering TM, Caplan AI, Goldberg VM, Yoo JU.

Source

Skeletal Research Center, Case Western Reserve University, Cleveland, Ohio 44106, USA. bxj9@po.cwru.edu

Abstract

A culture system that facilitates the chondrogenic differentiation of rabbit bone marrow-derived mesenchymal progenitor cells has been developed. Cells obtained in bone marrow aspirates were first isolated by monolayer culture and then transferred into tubes and allowed to form three-dimensional aggregates in a chemically defined medium. The inclusion of 10(-7) M dexamethasone in the medium induced chondrogenic differentiation of cells within the aggregate as evidenced by the appearance of toluidine blue metachromasia and the immunohistochemical detection of type II collagen as early as 7 days after beginning three-dimensional culture. After 21 days, the matrix of the entire aggregate contained type II collagen. By 14 days of culture, there was also evidence for type X collagen present in the matrix and the cells morphologically resembled hypertrophic chondrocytes. However, chondrogenic differentiation was achieved in only approximately 25% of the marrow cell preparations used. In contrast, with the addition of transforming growth factor-beta 1 (TGF-beta 1), chondrogenesis was induced in all marrow cell preparations, with or without the presence of 10(-7) M dexamethasone. The induction of chondrogenesis was accompanied by an increase in the alkaline phosphatase activity of the aggregated cells. The results of RT-PCR experiments indicated that both type IIA and IIB collagen mRNAs were detected by 7 days postaggregation as was mRNA for type X collagen. Conversely, the expression of the type I collagen mRNA was detected in the preaggregate cells but was no longer detectable at 7 days after aggregation. These results provide histological, immunohistochemical, and molecular evidence for the in vitro chondrogenic differentiation of adult mammalian progenitor cells derived from bone marrow.

PMID: 9457080    [PubMed – indexed for MEDLINE]

A Detailed Study And Analysis On Growth Differentiation Factors GDFs Which Influence Growth And Height

One group of growth factors which seem to really come up a lot in the research besides the bone morphogenetic proteins (BMPs) are the Growth Differentiation Factors (GDFs). The GDFs in general a a sub-group of the larger TGF-Beta superfamily of growth factors which have some role in development with around 30 combined total elements found so far.

In the past we saw that some GDFS, like GDF-5 and GDF-2 seem to have pro chondrogenic properties. From the wikipedia article on Growth Differentiation Factors I find that there is a GDF 1, 2, 3, 5, 6, 8, 9, 10, 11, and 15. Of the chart in the article, I would guess that the GDF2,3,5, and 10 are the most important ones for bone formation and development so these will be the only GDFs I will be focusing and doing any type of research on for the post. GDF2 is also known as BMP-9, GDF3 is also known as VGR-2, GDF10 is also known as BMP-3b.

GDF-5

From the R&D Systems website I would learn further about the functions and nature of the GDF-5…

“…It can be secreted by precartilagenous mesenchymal condensations involved in the formation of digits. It is also produced by fibroblasts, articular cartilage chondrocytes, and odontoblasts. GDF-5 actions may be mediated by the TGF-beta superfamily receptors ALK-6, BMP-RII, or Act-RII.“

This would suggest that it is secreted in the earlier stages of pre-natal embryo and fetal development since the fingers and toes are grown from their release. As for the fibroblasts and the articular cartilage chondrocytes, it shows that the GDF probably has not just some bone cell function, but also cartilage cell function. From the Medical Dictionary website I would learn that odontoblasts are “one of the connective tissue cells that deposit dentin and form the outer surface of the dental pulp”

The R&D Systems website would be more helpful in explaining the importance and influence of at least the GDF-5…

“The majority of GDF-5 research has centered on embryogenesis and on the development of joints in particular. GDF-5 has an apparent role in the formation of some synovial joints of the digits. GDF-5 may contribute to the formation of the early cartilage mass by promoting mesenchymal transformation to cartilage”

This suggest that while the entire array of functions of GDF-5 may not have been completely discovered, there is a lot of evidence in showing the link between GDF-5 and the development of joints. It seems that the synovial joints require this growth factor. At least for embryos and developing fetuses, the GDF-5 seems to be get the initial cartilage to form from mesenchymal stem cells. For our height increase interest, this shows that maybe it is possible still for fully mature grown up adults to get GDF-5 into their bone marrow to cause some cartilage formation as well.

Further on…

“Finally, after formation of the synovial cavity (see Figure 1c), GDF-5 may direct tendon and ligament formation around the joint, and induce cartilage expansion (thus bone lengthening) in the residual cartilage of bones associated with the synovial joint”

This shows that the GDF-5 has a way of directing the direction and arrangement of other tissue formation and postioning around the synovial joint, which it also has a influence on development on. It may appear that it would be the GDF-5 that is the real growth factor cause for endochondral ossification in the first place. The sentence suggest directly that the entire reason the cartilage even expands in the first place is from the action of GDF-5.

GDF-3

From a database on the National Institute Of Health website as a summary it states…

“The protein encoded by this gene is a member of the bone morphogenetic protein (BMP) family and the TGF-beta superfamily. This group of proteins is characterized by a polybasic proteolytic processing site which is cleaved to produce a mature protein containing seven conserved cysteine residues. The members of this family are regulators of cell growth and differentiation in both embryonic and adult tissues.”

The summary is not that useful but as for function I refer to the study “Mutation of the bone morphogenetic protein GDF3 causes ocular and skeletal anomalies.” The study suggest that the GDF-3 has at least some involvement in the development in some of the eye parts. When the GDF-3 creating gene is removed from tested animals, there is clear signs of development maladies. From paper “GDF6, a novel locus for a spectrum of ocular developmental anomalies.” it would seem that the GDF-6 besides the GDF-3 also has a role in ocular development.

From paper “Growth differentiation factor 3 is induced by bone morphogenetic protein 6 (BMP-6) and BMP-7 and increases luteinizing hormone receptor messenger RNA expression in human granulosa cells.” I would learn that it is possible to induce GDF-3 with BMP-6 or BMP-7 and that it has an inhibitory effect on the BMP cytokines. This idea would by validated by paper “GDF3, a BMP inhibitor, regulates cell fate in stem cells and early embryos.” What is startling from the short abstract is to learn that in both mouse and human stem cells, the GDF-3 is expressed a lot by the stem cells in pluripotent form. The conclusion give us another clue on maybe how to reverse or at least hold off on the differentiation process of stem cells so we can control how it changes over time.

“Furthermore, we use gain- and reduction-of-function to show that in a species-specific manner, GDF3 regulates both of the two major characteristics of embryonic stem cells: the ability to maintain the undifferentiated state and the ability to differentiate into the full spectrum of cell types.”

From paper “GDF3 at the crossroads of TGF-beta signaling.” we again see that the GDF-3 has a huge influence on undifferentiated embryonic stem cells which are still pluripotent in nature. The researchers conclude with “Chen and colleagues found that GDF-3 acts as a nodal-like TGF-beta ligand. These combined findings raise the intriguing possibility that GDF-3 acts as a bi-functional protein, to regulate the balance between the two modes of TGF-beta signaling.”

This raises the point that it seems to both help and inhibit many different types of growth factors in the TGF-Beta superfamily. It regulates a balance, so it can get the TGF-Beta groups to either increase or decrease. Like the GDF-5, it is becoming more and more clear that it has a huge influence on very early development and can be one of the keys to determining whether one’s height will be tall or short.

GDF-2

As for the sub-unit the growth differentiation factor 2, aka BMP-9 I used the source Wikigenes to get my information. From the sources posted it does seem that the GDF-2 aka BMP-9 has some chondrogenesis abilities. It also has some osteogenic abilities since rats bred without the GDF-2 encoded gene did inhibit some osteogenic development problems.

GDF-10

From the list of GDF-s on the original wikipedia chart, I have decided only to research and evaluate the research importance of GDF-5, 2, 3, and 10 since they seem to have some roles and involvement in the bones and cartilage development. Many of the other GDFs are involved in neuron or muscular development. For the GDF-10 element, again I would use its Wikigenes profile page as the only source for reference. It looks credible and well researched, even if the creation of the page did not involve combing through every single PubMed study ever linked or mentions the GDF-10 sub-unit. The GDF-10 seems to be very much related to the BMP-3 so it is also named BMP-3b.

The first major claim made by the site is during embryogenesis the GDF-10 has a role in formation of the bones in the skull and the vertebrate. As for the biological context of the GDF-10 we find that it has multiple roles in the cell differentiation for the formation of the skeletal structure. The mRNA for it is found in both prenatal and post natal individual’s bones.

There is a 2nd Wikigenes page on the GDF-10 where more genetic related information is found which I didn’t go through.

GDF-9

There is a Wikigenes page for GDF-9. From some studies off of PudMed HERE I would learn that the GDF-9 has function in female ovary, non mature egg development. They are secreted by oocytes in growing ovarian follicles.

From a paper on GDF-9 “Growth differentiation factor-9 is required during early ovarian folliculogenesis”  I would learn that at least one of the functions of the GDF-9 is required for ovarian folliculogenesis. The researchers conclude their abstract with…”GDF-9 is the first oocyte-derived growth factor required for somatic cell function in vivo.”

It would seem that even with its Wikipedia article, there is no mention of any development with bones or cartilage

Conclusion:

Overall the entire group of Growth Differentiation Factors has a major influence on the development process of every single type of cell in the body. It has been rather difficult in being able to separate and identify the specific GDF types which only focus on the development of either the bone or cartilage. Most of the GDFs have multiple functions.

However there are some studies which show that at least one of the GDF really has a direct influence on endochondral ossification and human growth. From the paper “Mechanisms of GDF-5 action during skeletal development” we would learn that transgenic mice that has their ability to recieve GDF removed showed many different types of genetic disorders of the limbs including chondrodysplasia. There is shortening of the appendicular skeleton and also either no or abnormal development of the joints. From Wikipedia I would learn that the term “appendicular skeleton” actually refers to the bones that make up the limbs aka appendages. This means all the bones in the torso, neck , and head are not part of the appendicular skeleton. The researchers decided to test to see how important the GDF-5 is in skeletal development. They took young chickens and overexpressed the gene that makes this protein. The result is that the overall skeletal length or amount of skeleton increased by 37.5% which is contributed to increases in the number of chondrocytes. For this nearly amazing growth factor, the researchers say it can do all these functions.

GDF-5 can…

  • Increase the size of the early cartilage condensation and the later developing skeletal element
  • Increases chondrogenesis in a dose-dependent manner.
  • Might act at these stages by increasing cell adhesion, a critical determinant of early chondrogenesis
  • At later stages of skeletal development GDF-5 can increase proliferation of chondrocytes
  • In controlling the size of skeletal elements and provides a possible explanation for the variation in the severity of skeletal defects resulting from mutations in GDF-5.

At this point I am going to focus almost all of my research on the Growth Differentiation Factors on the GDF-5 and a little on GDF-3. What I might even suggest at this stage is that the GDF-5 may be one of the most critical elements in our research.