Increase disc height with GDF-5 and BMP-7

GDF-5 stands for Growth Differentiation Factor Number 5 and is encoded by the gene of the same name.  It is a regulator of cell growth.  BMP-7(Bone Morphogenic Protein 7) is also known as Osteogenic Protein -1 or OP-1.  Like GDF-5, it is encoded by the gene of the same name BMP7.  BMP-7 plays an important part of transforming MSCs into cartilage and bone.  Generally, cartilage increasing height in the long bones and bone increasing height in other types of bones.

[Study progress of growth differentiation factor 5 or osteogenic protein 1[BMP-7] injection into a degenerated disc]

"To review the advance in the experimental studies and evaluate the potential therapeutic application of the growth differentiation factor 5(GDF-5) and osteogenic protein 1 (OP-1) in intervertebral disc degeneration. The growth factor was one of the most potential proteins in curing the intervertebral disc degeneration. In vitro[In an actual organism where compounds are subject to negative feedback], exogenous GDF-5 or OP-1 increased the deoxyribonucleic acid and proteoglycan contents of both nucleus pulposus and annlus fibrosis cells types significantly[nucleus pulposus is what reduces disc compression so possible increase in height]. GDF-5 at 200 ng/mL or OP-1 significantly stimulated proteoglycan synthesis and collagen synthesis[Collagen is what determines bone elasticity, which could result in more stretchable bones]. In vivo, the injection of GDF-5 (100 microg) or OP-1(100 microg in 10 microL 5% lactose) resulted in a restoration of disc height, improvement of magnetic resonance imaging scores, and histologic grading scores had statistical significance. A single injection of GDF-5 or OP-1 has a reparative capacity on intervertebral discs, presumably based on its effect to stimulate matrix metabolism of intervertebral disc cells and enhance extracellular matrix production."

So, GDF-5 and BMP-7 can reduce height loss due to intervertebral disc degeneration.

The effect of recombinant human osteogenic protein-1 on growth plate repair in a sheep model. 

"Injuries to the growth plate in children can result in bone bridge formation, which ultimately lead to limb length and angular deformities. The histological and molecular changes associated with growth plate repair following the Langenskiöld procedure, a surgical technique used to remove impeding bone bridges, in conjunction with administration of recombinant human osteogenic protein-1 (rhOP-1) were examined using a sheep model. Following treatment with rhOP-1 there was an increase in the height of the growth plate immediately adjacent to the defect compared to untreated animals[But the growth plate heights of the non-defective areas of the growth plate remained the same]. The expression of type I collagen, osteopontin and decorin were observed in the growth plate adjacent to the defect in the untreated animals at day 56, but this response was accelerated in the rhOP-1 treated animals, with these molecules seen as early as day 7. Therefore, treatment with rhOP-1 initiated a complex response that was both chondrogenic and osteogenic in nature." 

BMP-7 increases growth rate definitely but it could result in an increase in final height if it increased chondrocyte proliferative capacity.  

"In vitro studies in rat calvarial cells, ATDC5 cells, mouse embryonic long bone cultures, transplanted perichondrial cultures and articular cartilage cultures have reported an increase in the synthesis of type I1 collagen and proteoglycans following the administration of recombinant human OP-1(rhOP-I)"<-BMP-7 increases synthesis of Type II(Cartilage) Collagen and Proteoglycans

"The increase in type I1 collagen and proteoglycan synthesis is paralleled with an increase in the mRNA expression for hyaluronan synthase-2 and CD44, molecules necessary for matrix retention"[CD44 is a receptor for hyaluronic acid]  BMP-7 seems to play a role in growth plate modeling to repair defects but does not seem to induce height increase on it's own.

Induction of chondrogenesis from human embryonic stem cells without embryoid body formation by bone morphogenetic protein 7 and transforming growth factor beta1. 

"Articular cartilage is an avascular tissue with precise polarity and organization comprising 3 distinct functional zones: surface, middle, and deep. The present study was undertaken to determine the in vitro chondrogenic potential of bone morphogenetic protein 7 (BMP-7) and transforming growth factor beta1 (TGFbeta1)-induced human ESC differentiation toward the articular cartilage phenotype. 
 Dissociated single human ESCs were cultured and passaged on a gelatin-coated flask. The human ESCs were cultured as an aggregate in a pellet culture system for 14 days in basal chondrogenic medium (CM), CM with TGFbeta1, CM with BMP-7, or CM with both TGFbeta1 and BMP-7. 
The size and wet weight of the cartilage pellets and glycosaminoglycan levels increased, with the smallest, intermediate, and greatest increases, respectively, observed with CM plus TGFbeta1 treatment, CM plus BMP-7 treatment, and CM plus TGFbeta1 and BMP-7 treatment (compared with CM treatment alone). The largest size and highest weight of the pellet was in the group in which TGFbeta1 and BMP-7 were added to the medium. However, expression of the genes for cartilage-specific aggrecan and type II collagen II, as assessed by determination of messenger RNA levels, was highest in the BMP-7-treated group. Superficial zone protein (SZP)/lubricin, a marker of the superficial zone articular chondrocyte, was not detectable under identical culture conditions. 
These results demonstrate an efficient and reproducible model system of human ESC-induced chondrogenesis." 

So, looking for compounds and activities that increase levels of BMP-7 is definitely worth investigating. 

"The mean weight of 7 pellets per group was 1.51 mg in the CM with TGFβ1 and BMP-7 group, 1.30 mg in the CM with BMP-7 group, 0.67 mg in the CM with TGFβ1 group, and 0.40 mg in the CM alone group"<-So BMP-7 may be more chondrogenic than TGF-Beta but it could also accelerate chondrocytes towards terminal differentiation faster.

"Pellets from the CM with TGFβ1 group showed tightly packed cell density, but weak immunostaining for type II collagen. The centers of the pellets from the CM with BMP-7 group appeared undifferentiated, while their periphery showed well-differentiated chondrocytes and stained strongly for GAG and type II collagen"

New insights into BMP-7 mediated osteoblastic differentiation of primary human mesenchymal stem cells. 

"BMP-7 (OP-1) is currently used clinically in revision of posterolateral spine fusions and long bone non-unions. The current study characterizes BMP-7 induced gene expression during early osteoblastic differentiation of human mesenchymal stem cells (hMSC). Primary hMSC were treated with BMP-7 for 24 or 120 h and gene expression across the entire human genome was evaluated using Affymetrix HG-U133 Plus 2.0 Arrays. 955 probe sets representing 655 genes and 95 ESTs were identified as differentially expressed and were organized into three major expression profiles (Profiles A, B and C) by hierarchical clustering. Genes from each profile were classified according to biochemical pathway analyses. Profile A, representing genes upregulated by BMP-7, revealed strong enrichment for established osteogenic marker genes, as well as several genes with undefined roles in osteoblast function, including MFI2, HAS3, ADAMTS9, HEY1, DIO2 and FGFR3. A functional screen using siRNA suggested roles for MFI2, HEY1 and DIO2 in osteoblastic differentiation of hMSC. Profile B contained genes transiently downregulated by BMP-7, including numerous genes associated with cell cycle regulation. Follow-up studies confirmed that BMP-7 attenuates cell cycle progression and cell proliferation during early osteoblastic differentiation. Profile C, comprised of genes continuously downregulated by BMP-7, exhibited strong enrichment for genes associated with chemokine/cytokine activity. Inhibitory effects of BMP-7 on cytokine secretion were verified by analysis of enriched culture media. Potent downregulation of CHI3L1, a potential biomarker for numerous joint diseases, was also observed in Profile C. A focused evaluation of BMP, GDF and BMP inhibitor expression elucidated feedback loops modulating BMP-7 bioactivity. BMP-7 was found to induce BMP-2 and downregulate GDF5 expression. Transient knockdown of BMP-2 using siRNA demonstrated that osteoinductive properties associated with BMP-7 are independent of endogenous BMP-2 expression. Noggin was identified as the predominant inhibitor induced by BMP-7 treatment.." 

Genetic variation in the GDF5 region is associated with osteoarthritis, height, hip axis length and fracture risk: the Rotterdam study. 

A polymorphism (rs143383; T to C) near the GDF5 gene has been associated with height.   
To study the association between genetic variation in the GDF5 region and radiographic osteoarthritis (ROA) susceptibility, height, bone size parameters and fracture risk in a large population-based cohort of Caucasian elderly subjects. 
6365 men and women had genotype data available. ROA was defined as a Kellgren/Lawrence (K/L) score > or =2 for hand, knee and hip joints. CTX-II levels, height, bone mineral density (BMD), bone size and fracture risk were also assessed.
rs143383 and three highly correlated single nucleotide polymorphisms (SNPs) in the GDF5 region were found to be independently associated with OA, height, bone size and fracture risk in women. Women with homozygotes for the rs143383 C allele had a 37% lower risk for hand OA (p = 8 x 10(-6)) and a 28% lower risk for knee OA (p = 0.003). In addition, they were 1.1 cm taller (p = 0.001), had a larger hip axis length (HAL) (p = 4 x 10(-4)) and had a 29% increased risk of incident non-vertebral fractures (p = 0.02). No associations with hip OA or BMD were detected. No associations were found in men. 
It also replicates previous association between GDF5 variation and height. Furthermore, our findings for HAL suggest that GDF5 action is primarily directed to the long bones, rather than the axial skeleton."

"GDF5 can induce ectopic cartilage and bone formation in vivo and in vitro and is present in adult human cartilage"<-thus maybe GDF5 can induce mesenchymal chondrogenesis in the epiphyseal bone marrow.

One possibility as to why the gene has an effect on women and not on men is that it may be a sex linked trait. Of course, the fact that the trait was noticed in homozygous genes makes this possibility less likely.  "sex-specific hormones, like androgens and oestrogens, might be involved in GDF5 regulation"  It could be that this particular gene is not hemizygous(not functional with only one allele).  Also, this gene may only interact with female specific compounds.  One way to test this would be to examine the effects of GDF-5 on people who are XXY(Klinefelter's Syndrome).  No such studies have yet been done.

Role of hypoxia and growth and differentiation factor-5 on differentiation of human mesenchymal stem cells towards intervertebral nucleus pulposus-like cells.

"We compared the standard chondrogenic protocol using transforming growth factor beta-1 (TGFß) to the effects of hypoxia, growth and differentiation factor-5 (GDF5), and coculture with bovine nucleus pulposus cells (bNPC). The efficacy of molecules recently discovered as possible nucleus pulposus (NP) markers to differentiate between chondrogenic and IVD-like differentiation was evaluated. MSCs were isolated from human bone marrow and encapsulated in alginate beads. Beads were cultured in DMEM (control) supplemented with TGFß or GDF5 or under indirect coculture with bNPC. All groups were incubated at low (2 %) or normal (20 %) oxygen tension for 28 days. Hypoxia increased aggrecan and collagen II gene expression in all groups. The hypoxic GDF5 and TGFß groups demonstrated most increased aggrecan and collagen II mRNA levels and glycosaminoglycan accumulation. Collagen I and X were most up-regulated in the TGFß groups. From the NP markers, cytokeratin-19 was expressed to highest extent in the hypoxic GDF5 groups; lowest expression was observed in the TGFß group. Levels of forkhead box F1 were down-regulated by TGFß and up-regulated by coculture with bNPC. Carbonic anhydrase 12 was also down-regulated in the TGFß group and showed highest expression in the GDF5 group cocultured with bNPC under hypoxia. Trends in gene expression regulation were confirmed on the protein level using immunohistochemistry. We conclude that hypoxia and GDF5 may be suitable for directing MSCs towards the IVD-like phenotype."

Even though GDF5 mainly directs towards intravertebral disc cells it may still help induce endochondral ossification.  And interverterbral disc height influences height in the spine.


Growth differentiation factor 5 modulation of chondrogenesis of self-assembled constructs involves gap junction-mediated intercellular communication.

" novel scaffold-free self-assembled cartilage construct has been generated and used to repair particular chondral defects effectively. We hypothesize that gap junction intercellular communication (GJIC) plays a critical role in the development of self-assembled constructs upon GDF-5 induction. In this study, we investigated the effect of connexin 43 (C×43) mediated GJIC on GDF-5 modulation of chondrogenesis from two aspects, cell monolayer culture and 3-D self-assembly culture. We induced cells or self-assembled constructs with chondrogenic media (CM), growth differentiation factor 5 (GDF-5) or 1-heptanol for 3 weeks. At the end of that time, the results of quantitative fluorescence redistribution after photobleaching (FRAP) assay and immunofluorescence demonstrated that GDF-5 improved both GJIC and chondrogenic differentiation to a significant degree while 1-heptanol nearly offset the expected improvements in chondrogenesis. Biochemical assay and histology showed that GDF-5 can obviously enhance GAG, C×43 and type II collagen expressions. Conversely, we also showed that while 1-heptanol weakened GAG and type II collagen expression in self-assembled constructs, it had no effect on C×43 expression. Furthermore, real-time polymerase chain reaction showed that GDF-5 enhanced GAG and type II collagen transcription while 1-heptanol reduced them, but was affectless on C×43 transcription. This suggests that the generation of scaffold-free self-assembled cartilage from human mesenchymal stem cells upon GDF-5 induction may be mediated, at least in part, via the modulation of GJIC."

"[The] condensation stage of chondrogenesis is mediated by intercellular communication, most probably via gap junctions"

"contact between mesenchymal cells is necessary for the intercellular signal exchanges, which contribute to the initiation of condensation and the subsequent formation of chondroprogenitor cells."

" 100 ng/mL of GDF-5 was highly effective at inducing the differentiation of fibroblasts, periosteum-derived cells, and stem cells into chondrocytes while at the same time promoting the secretion of a chondrocyte-specific collagen and proteoglycan matrix"