A missense GDF5 variant causes brachydactyly type A1 and multiple-synostoses syndrome 2

Objective

This study aimed to identify the molecular defects and clinical manifestations in a Chinese family with brachydactyly (BD) type A1 (BDA1) and multiple-synostoses syndrome 2 (SYNS2).

Methods

A Chinese family with BDA1 and SYNS2 was enrolled in this study. Whole-exome sequencing was used to analyze the gene variants in the proband. The sequences of the candidate pathogenic variant in GDF5 was validated via Sanger sequencing. I-TASSER and PyMOL were used to analyze the functional domains of the corresponding mutant proteins.

Results

The family was found to have an autosomal-dominantly inherited combination of BDA1 and SYNS2 caused by the S475N variant in the GDF5 gene. The variant was located within the functional region, and the mutated residue was found to be highly conserved among species. Via bioinformatic analyses, we predicted this variant to be deleterious, which perturb the protein function. The substitution of the negatively charged amino acid S475 with the neutral N475 was predicted to disrupt the formation of salt bridges with Y487 and impair the structure, stability, and function of the protein, consequently, the abnormalities in cartilage and bone development ensue.

Conclusions

A single genetic variant (S475N) which disrupt the formation of salt bridges with Y487, in the interface of the antagonist- and receptor-binding sites of GDF5 concurrently causes two pathological mechanisms. This is the first report of this variant, identified in a Chinese family with BDA1 and SYNS2.

Decellularized nucleus pulposus matrix/chitosan hybrid hydrogel combined with nucleus pulposus stem cells and GDF5-loaded microspheres for intervertebral disc degeneration prevention

BACKGROUND

Intervertebral disc degeneration (IDD) is considered an important pathological basis for spinal degenerative diseases. Tissue engineering is a powerful therapeutic strategy that can effectively restore the normal biological properties of disc units. In this study, hydrogels loaded with growth/differentiation factor 5 (GDF5) and stem cells were combined to provide an effective strategy for nucleus pulposus regeneration.

METHODS

Nucleus pulposus stem cells (NPSCs) were obtained by low-density inoculation and culture, and their stem cell characteristics were verified by flow cytometry and a tri-lineage-induced differentiation experiment. A decellularized nucleus pulposus matrix (DNPM) and chitosan hybrid hydrogel was prepared, and GDF5-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres were incorporated into the hydrogels to obtain a composite hydrogels with GDF5-loaded microspheres. Taking bone marrow mesenchymal stem cells (BMSCs) as a reference, the effect of composite hydrogels with GDF5-loaded microspheres on the chondrogenic differentiation of NPSCs was evaluated. A model of intervertebral disc degeneration induced by acupuncture on the tail of rats was constructed, and the repair effect of composite hydrogels with GDF5-loaded microspheres combined with NPSCs on IDD was observed.

RESULTS

Stem cell phenotype identification, stemness gene expression and tri-lineage-induced differentiation confirmed that NPSCs had characteristics similar to those of BMSCs. The rat DNPM and chitosan hybrid hydrogels had good mechanical properties, and the GDF5-loaded microspheres sustainably released GDF5. NPSCs grew normally in the composite hydrogels and gradually expressed a chondrocyte phenotype. Animal experiments showed that the composite hydrogels with GDF5-loaded microspheres combined with NPSCs effectively promoted nucleus pulposus regeneration and that the effect of the hydrogels on the repair of IDD was significantly better than that of BMSCs.

CONCLUSION

GDF5-loaded microspheres combined with DNPM/chitosan composite hydrogels can effectively promote the differentiation of NPSCs into nucleus pulposus-like cells and effectively preventIDD.

GDF5 deficiency prevents cardiac rupture following acute myocardial infarction in mice

BACKGROUND

We previously showed that growth differentiation factor 5 (GDF5) limits infarct expansion post-myocardial infarction (MI). We now examine the acute post-MI role of GDF5 in cardiac rupture.

METHODS AND RESULTS

Following permanent ligation of the left anterior descending artery, GDF5 deficiency (i.e., GDF5 knockout mice) reduced the incidence of cardiac rupture (4/24 vs. 17/24; P < .05), and improved survival over 28-d compared to wild-type (WT) mice (79% vs. 25%; P < .0001). Moreover, at 3-d post-MI, GDF5-deficient mice manifest: (a) reduced heart weight/body weight ratio (P < .0001) without differences in infarct size or cardiomyocyte size; (b) increased infarct zone expression of Col1a1 (P < .05) and Col3a1 (P < .01), suggesting increased myocardial fibrosis; and (c) reduced aortic and left ventricular peak systolic pressures (P ≤ .05), suggesting reduced afterload. Despite dysregulated inflammatory markers and reduced circulating monocytes in GDF5-deficient mice at 3-d post-MI, reciprocal bone marrow transplantation (BMT) failed to implicate GDF5 in BM-derived cells, suggesting the involvement of tissue-resident GDF5 expression in cardiac rupture.

CONCLUSIONS

Loss of GDF5 reduces cardiac rupture post-MI with increased myocardial fibrosis and lower afterload, albeit at the cost of chronic adverse remodeling.

The association of growth differentiation factor 5 rs143383 gene polymorphism with osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Osteoarthritis (OA) is caused by a complex set of pathophysiological factors. The genetic factors involved in the occurrence and progress of the disease have been widely discussed by scholars. It was found that growth differentiation factor 5 (GDF5) gene polymorphisms may be linked to OA susceptibility, which has been controversial and needs to be further confirmed by an updated meta-analysis.

OBJECTIVES

We examined the association between GDF5 rs143383 single nucleotide polymorphism (SNP) and OA susceptibility.

METHODS

All relevant articles that met the criteria are retrieved and included, and the search deadline is June 2022. The allele frequencies and different genotype frequencies of GDF5 rs143383 loci in each study were extracted and statistically analyzed by R4.1.3 software, and the different genetic models were analyzed based on their odds ratio (OR) and 95% confidence interval (CI).

RESULTS

The meta-analysis explained that GDF5 rs143383 SNP was crucial correlated with OA in all patients with OA of knee, hip and hand. The codominant gene model in the whole crowd (OR = 1.17, 95% CI 1.07-1.27, P < 0.01) enlightened that OA was vitally associated with GDF5 gene polymorphism. At the same time, we did a subgroup analysis based on ethnicity. The codominant gene model (OR = 1.31, 95% CI 1.12-1.53, P < 0.01) in Asian population, the codominant homozygote model (OR = 1.28, 95% CI 1.14-1.43), codominant heterozygote gene model (OR = 1.12, 95% CI 1.01-1.23, P = 0.02), and dominant gene model (OR = 1.19, 95% CI 1.09-1.31, P < 0.01) in Caucasian are analyzed by subgroup analysis. It means that there is a momentous relationship between the GDF5rs143383 gene polymorphism and OA, especially among Caucasians. In addition, we also discussed different types of OA separately and discover that the GDF5rs143383 gene polymorphism was relevant for knee osteoarthritis (KOA) and hand osteoarthritis, and it was more significant in the Caucasian population. But due to the high heterogeneity in hip osteoarthritis, it could not be accurately concluded. Furthermore, we also analyzed the osteoarthritis of different genders and found that the GDF5 rs143383 SNP was associated with both men and women and was still significant in the Caucasian population.

CONCLUSION

We found a close association between osteoarthritis and GDF5rs143383SNP in this study. From the analysis of each group, we got the same conclusion in KOA and hand OA, but which need further verification in hip OA. Considering gender, we found a close relationship between GDF5 rs143383 SNP and OA of the knee, hip and hand, both for men and women. This conclusion is more obvious in Caucasian people.

BMP2 and GDF5 for Compartmentalized Regeneration of the Scapholunate Ligament

Background  Chronic injuries to the scapholunate ligament (SLIL) alter carpal kinematics and may progress to early degenerative osteoarthritis. To date, there is no consensus for the best method for SLIL reconstruction. This study aims to assess the use of growth factors (bone morphogenetic protein [BMP]2 and growth and differentiation factor 5 [GDF5]) for compartmentalized regeneration of bone and ligament in this multiphasic scaffold in a rabbit knee model. Case Description  A total of 100 µg of BMP2 and 30 µg of GDF5 were encapsulated into a heparinized gelatin-hyaluronic acid hydrogel and loaded into the appropriate compartment of the multiphasic scaffold. The multiphasic scaffold was implanted to replace the native rabbit medial collateral ligament ( n  = 16). The rabbits were randomly assigned to two different treatment groups. The first group was immobilized postoperatively with the knee pinned in flexion with K-wires for 4 weeks ( n  = 8) prior to sacrifice. The second group was immobilized for 4 weeks, had the K-wires removed followed by a further 4 weeks of mobilization prior to sample harvesting. Literature Review  Heterotopic ossification as early as 4 weeks was noted on gross dissection and confirmed by microcomputed tomography and histological staining. This analysis revealed formation of a bony bridge located within and over the ligament compartment in the intra-articular region. Biomechanical testing showed increased ultimate force of the ligament compartment at 4 weeks postimplantation consistent with the presence of bone formation and higher numbers of scaffold failures at the bone-tendon junction. This study has demonstrated that the addition of BMP2 and GDF5 in the bone-ligament-bone (BLB) scaffold resulted in heterotopic bone formation and failure of the ligament compartment. Clinical Relevance  The implantation of a three-dimensional-printed BLB scaffold alone demonstrated superior biomechanical and histological results, and further investigation is needed as a possible clinical reconstruction for the SLIL.

Fibular Agenesis and Ball-Like Toes Mimicking Preaxial Polydactyly: Prenatal Presentation of Du Pan Syndrome

Introduction

GDF5-BMPR1B signaling pathway-associated chondrodysplasias are a genetically heterogeneous group of conditions with significant phenotypic and genotypic overlap, consisting of Hunter-Thompson-type acromesomelic dysplasia, Grebe dysplasia, and Du Pan syndrome. Constituting a spectrum of clinical severity, these disorders are characterized by disproportionate short stature mainly involving middle and distal segments of the extremities. Du Pan syndrome represents the mildest end of this spectrum with less marked shortened limbs, fibular agenesis or hypoplasia, absence of frequent joint dislocations, and carpotarsal fusions with deformed phalangeal bones.

Case Presentation

Here, we report the first prenatal diagnosis of Du Pan syndrome based on the sonographic findings of bilateral fibular agenesis and ball-shaped toes mimicking preaxial polydactyly accompanying subtle brachydactyly in the family. GDF5 (NM_000557.5) sequencing identified a homozygous pathogenic variant c.1322T>C, p.(Leu441Pro) in the fetus and confirmed the carrier status in the mother.

Discussion

We suggest that the presence of bilateral fibular agenesis and the apparent image of preaxial polydactyly of the feet on prenatal ultrasound should alert suspicion to Du Pan syndrome, with the latter possibly being a sonographic pitfall. Alongside the fetal imaging, a detailed clinical examination of the expectant parents is also of great importance in establishing a preliminary diagnosis of Du Pan syndrome, as well as the other GDF5-BMPR1B-associated chondrodysplasias.

Skeletal Muscle-Derived Exosomal miR-146a-5p Inhibits Adipogenesis by Mediating Muscle-Fat Axis and Targeting GDF5-PPARγ Signaling

Skeletal muscle-fat interaction is essential for maintaining organismal energy homeostasis and managing obesity by secreting cytokines and exosomes, but the role of the latter as a new mediator in inter-tissue communication remains unclear. Recently, we discovered that miR-146a-5p was mainly enriched in skeletal muscle-derived exosomes (SKM-Exos), 50-fold higher than in fat exosomes. Here, we investigated the role of skeletal muscle-derived exosomes regulating lipid metabolism in adipose tissue by delivering miR-146a-5p. The results showed that skeletal muscle cell-derived exosomes significantly inhibited the differentiation of preadipocytes and their adipogenesis. When the skeletal muscle-derived exosomes co-treated adipocytes with miR-146a-5p inhibitor, this inhibition was reversed. Additionally, skeletal muscle-specific knockout miR-146a-5p (mKO) mice significantly increased body weight gain and decreased oxidative metabolism. On the other hand, the internalization of this miRNA into the mKO mice by injecting skeletal muscle-derived exosomes from the Flox mice (Flox-Exos) resulted in significant phenotypic reversion, including down-regulation of genes and proteins involved in adipogenesis. Mechanistically, miR-146a-5p has also been demonstrated to function as a negative regulator of peroxisome proliferator-activated receptor γ (PPARγ) signaling by directly targeting growth and differentiation factor 5 (GDF5) gene to mediate adipogenesis and fatty acid absorption. Taken together, these data provide new insights into the role of miR-146a-5p as a novel myokine involved in the regulation of adipogenesis and obesity via mediating the skeletal muscle-fat signaling axis, which may serve as a target for the development of therapies against metabolic diseases, such as obesity.

LINC00313 promotes the proliferation and inhibits the apoptosis of chondrocytes via regulating miR-525-5p/GDF5 axis

BACKGROUND

The present study aimed to explore the potentials of lncRNA LINC00313 in osteoarthritis (OA).

METHODS

qRT-PCR was performed to detect the expression of LINC00313 in OA tissues and cells. CCK-8 and EDU were used to detect cell proliferation. The ELISA test kit was conducted to detect the expression of inflammatory factors. Flow cytometry was used to detect the apoptosis rates. Western blot was applied to measure the protein expression. The luciferase reporter gene test was carried out to verify the relationship between miR-525-5p and LINC00313 or GDF5.

RESULTS

The data showed that the expression of LINC00313 was significantly down-regulated in OA tissues and cells. Functionally, LINC00313 promoted the proliferation of chondrocytes and suppressed the secretion of inflammatory factors and cell apoptosis. Moreover, LINC00313 functioned as a ceRNA to up-regulate the expression of GDF5 via sponging miR-525-5p. Luciferase and RNA pull-down assays further verified the interaction between miR-525-5p and LINC00313 (or GDF5). Moreover, overexpression of miR-525-5p or down-regulated GDF5 degraded the cellular functions of chondrocyte. Rescue experiments showed that the overexpression of miR-525-5p reversed the increase in cell viability and the decrease in pro-inflammatory factors and apoptosis rate mediated by LINC00313. The knockdown of GDF5 reversed the promotion of miR-525-5p knockdown on cell viability and the inhibition of pro-inflammatory factors and apoptosis rate.

CONCLUSIONS

LINC00313 inhibited the development of OA through regulating miR-525-5p/GDF5 axis. LncRNA LINC00313 can be used as a potential target for the treatment of OA.

Long non-coding RNA SNHG5 promotes the osteogenic differentiation of bone marrow mesenchymal stem cells via the miR-212-3p/GDF5/SMAD pathway

Background

The treatment of bone loss has posed a challenge to clinicians for decades. Thus, it is of great significance to identify more effective methods for bone regeneration. However, the role and mechanisms of long non-coding RNA small nucleolar RNA host gene 5 (SNHG5) during osteogenic differentiation remain unclear.

Methods

We investigated the function of SNHG5, Yin Yang 1 (YY1), miR-212-3p and growth differentiation factor 5 (GDF5) in osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) in vitro and in vivo. Molecular mechanisms were clarified by chromatin immunoprecipitation assay and dual luciferase reporter assay.

Results

We found SNHG5 expression was upregulated during osteogenesis of hBMSCs. Knockdown of SNHG5 in hBMSCs inhibited osteogenic differentiation while overexpression of SNHG5 promoted osteogenesis. Moreover, YY1 transcription factor directly bound to the promoter region of SNHG5 and regulated SNHG5 expression to promote osteogenesis. Dual luciferase reporter assay confirmed that SNHG5 acted as a miR-212-3p sponge and miR-212-3p directly targeted GDF5 and further activated Smad1/5/8 phosphorylation. miR-212-3p inhibited osteogenic differentiation, while GDF5 promoted osteogenic differentiation of hBMSCs. In addition, calvarial defect experiments showed knockdown of SNHG5 and GDF5 inhibited new bone formation in vivo.

Conclusion

Our results demonstrated that the novel pathway YY1/SNHG5/miR-212-3p/GDF5/Smad regulates osteogenic differentiation of hBMSCs and may serve as a potential target for the treatment of bone loss.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02781-8.

Association Analysis of GDF5 and Contributing Factors in Developmental Dysplasia of the Hip in Infants

BACKGROUND

Developmental dysplasia of the hip (DDH) is a developmental disorder which is reported to be associated with hip instability. When untreated, it can lead to irreversible joint damage. DDH is known to be a multifactorial disease involving genetic, mechanical and environmental factors. The greatest causative potential is attributed to the genetic component. Growth Differentiation Factor 5 (GDF5) is among the most studied genes associated with processes of regeneration and maintenance of joints. The aim of this work was to analyse the association of SNP rs143383 in the GDF5 gene and the occurrence of DDH, along with association with various contributing factors in the Caucasian population.

MATERIAL AND METHODS

A total of 118 samples were analysed for the presence of the mutation. DNA was isolated from all individuals from peripheral blood. SNP rs143383 in the GDF5 gene was genotyped using the TaqMan assay. A standard chi-square test was used to compare allele and genotype distributions in patients and healthy controls.

RESULTS

The association analysis of genotypes of DDH and rs143383 revealed a significant association. Also, the association of GDF5 and selected contributing factors was statistically significant in female gender (p=0.002), family history (p&lt;0.001), count of pregnancy (p=0.009), laterality of hip involvement and initial US examination.

CONCLUSIONS

1. The results indicate an important effect of rs143383 polymorphism in the GDF5 gene on DDH development. 2. However, our results also suggest that rs143383 is not the only contributing factor in the genetic component of DDH.

Genetic Study of IL6, GDF5 and PAPPA2 in Association with Developmental Dysplasia of the Hip

Background: Developmental dysplasia of the hip (DDH) is one of the most prevalent skeletal disorders. DDH is considered a pathologic condition with polygenic background, but environmental and mechanic factors significantly contribute to its multifactorial etiology. Inheritance consistent with autosomal dominant type has also been observed. Single-nucleotide polymorphisms (SNPs) in various genes mostly related to formation of connective tissue are studied for a possible association with DDH. Methods: We genotyped three SNPs, rs1800796 located in the promoter region of the IL6 gene, rs143383 located in the 5′ untranslated region (UTR) of the GDF5 gene and rs726252 located in the fifth intron of the PAPPA2 gene. The study consisted of 45 subjects with DDH and 85 controls from all regions of Slovakia. Results: Association between DDH occurrence and studied genotypes affected by aforementioned polymorphisms was confirmed in the case of rs143383 in the GDF5 gene (p = 0.047), where the T allele was over-expressed in the study group. Meanwhile, in the matter of IL6 and PAPPA2, we found no association with DDH (p = 0.363 and p = 0.478, respectively). Conclusions: These results suggest that there is an association between DDH and GDF5 polymorphisms and that the T allele is more frequently presents in patients suffering from DDH.

Fibroblastic differentiation of mesenchymal stem/stromal cells (MSCs) is enhanced by hypoxia in 3D cultures treated with bone morphogenetic protein 6 (BMP6) and growth and differentiation factor 5 (GDF5)

INTRODUCTION

Culture conditions and differentiation cocktails may facilitate cell maturation and extracellular matrix (ECM) secretion and support the production of engineered fibroblastic tissues with applications in ligament regeneration. The objective of this study is to investigate the potential of two connective tissue-related ligands (i.e., BMP6 and GDF5) to mediate collagenous ECM synthesis and tissue maturation in vitro under normoxic and hypoxic conditions based on the hypothesis that BMP6 and GDF5 are components of normal paracrine signalling events that support connective tissue homeostasis.

METHODS

Human adipose-derived MSCs were seeded on 3D-printed medical-grade polycaprolactone (PCL) scaffolds using a bioreactor and incubated in media containing GDF5 and/or BMP6 for 21 days in either normoxic (5% oxygen) or hypoxic (2% oxygen) conditions. Constructs were harvested on Day 3 and 21 for cell viability analysis by live/dead staining, structural analysis by scanning electron microscopy, mRNA levels by RTqPCR analysis, and in situ deposition of proteins by immunofluorescence microscopy.

RESULTS

Pro-fibroblastic gene expression is enhanced by hypoxic culture conditions compared to normoxic conditions. Hypoxia renders cells more responsive to treatment with BMP6 as reflected by increased expression of ECM mRNA levels on Day 3 with sustained expression until Day 21. GDF5 was not particularly effective either in the absence or presence of BMP6.

CONCLUSIONS

Fibroblastic differentiation of MSCs is selectively enhanced by BMP6 and not GDF5. Environmental factors (i.e., hypoxia) also influenced the responsiveness of cells to this morphogen.

A GDF5 frameshift mutation segregating with Grebe type chondrodysplasia and brachydactyly type C+ in a 6 generations family: Clinical report and mini review

Different mutations in the Growth/Differentiation Factor 5 gene (GDF5) have been associated with varying types of skeletal dysplasia, including Grebe type chondrodysplasia (GTC), Hunter-Thompson syndrome, Du Pan Syndrome and Brachydactyly type C (BDC). Heterozygous pathogenic mutations exert milder effects, whereas homozygous mutations are known to manifest more severe phenotypes. In this study, we report a GDF5 frameshift mutation (c.404delC) segregating over six generations in an extended consanguineous Pakistani family. The family confirmed that both GTC and BDC are part of the GDF5 mutational spectrum, with severe GTC associated with homozygosity, and with a wide phenotypic variability among heterozygous carriers, ranging from unaffected non-penetrant carriers, to classical BDC and to novel unclassified types of brachydactylies.

GDF5 mutation case report and a systematic review of molecular and clinical spectrum: Expanding current knowledge on genotype-phenotype correlations

INTRODUCTION

Brachydactyly is a bone development abnormality presenting with variable phenotypes and different transmission patterns. Mutations in GDF5 (Growth and Differentiation Factor 5, MIM *601146) account for a significant amount of cases. Here, we report on a three-generation family, where the proband and the grandfather have an isolated brachydactyly with features of both type A1 (MIM #112500) and type C (MIM #113100), while the mother shows only subtle hand phenotype signs.

MATERIALS AND METHODS

Whole Exome Sequencing (WES) was performed on the two affected individuals. An in-depth analysis of GDF5 genotype-phenotype correlations was performed through literature reviewing and retrieving information from several databases to elucidate GDF5-related molecular pathogenic mechanisms.

RESULTS

WES analysis disclosed a pathogenic variant in GDF5 (NM_000557.5:c.157dup; NP_000548.2:p.Leu53Profs*41; rs778834209), segregating with the phenotype. The frameshift variant was previously associated with Brachydactyly type C (MIM #113100), in heterozygosity, and with the severe Grebe type chondrodysplasia (MIM #200700), in homozygosity. In-depth analysis of literature and databases allowed to retrieve GDF5 mutations and correlations to phenotypes. We disclosed the association of 49 GDF5 pathogenic mutations with eight phenotypes, with both autosomal dominant and recessive transmission patterns. Clinical presentations ranged from severe defects of limb morphogenesis to mild redundant ossification. We suggest that such clinical gradient can be linked to a continuum of GDF5-activity variation, with loss of GDF5 activity underlying bone development defects, and gain of function causing disorders with excessive bone formation.

CONCLUSIONS

Our analysis of GDF5 pathogenicity mechanisms furtherly supports that mutation and zygosity backgrounds resulting in the same level of GDF5 activity may lead to similar phenotypes. This information can aid in interpreting the potential pathogenic effect of new variants and in supporting an appropriate genetic counseling.

Non-viral Gene Delivery Methods for Bone and Joints

Viral carrier transport efficiency of gene delivery is high, depending on the type of vector. However, viral delivery poses significant safety concerns such as inefficient/unpredictable reprogramming outcomes, genomic integration, as well as unwarranted immune responses and toxicity. Thus, non-viral gene delivery methods are more feasible for translation as these allow safer delivery of genes and can modulate gene expression transiently both in vivo, ex vivo, and in vitro. Based on current studies, the efficiency of these technologies appears to be more limited, but they are appealing for clinical translation. This review presents a summary of recent advancements in orthopedics, where primarily bone and joints from the musculoskeletal apparatus were targeted. In connective tissues, which are known to have a poor healing capacity, and have a relatively low cell-density, i.e., articular cartilage, bone, and the intervertebral disk (IVD) several approaches have recently been undertaken. We provide a brief overview of the existing technologies, using nano-spheres/engineered vesicles, lipofection, and in vivo electroporation. Here, delivery for microRNA (miRNA), and silencing RNA (siRNA) and DNA plasmids will be discussed. Recent studies will be summarized that aimed to improve regeneration of these tissues, involving the delivery of bone morphogenic proteins (BMPs), such as BMP2 for improvement of bone healing. For articular cartilage/osteochondral junction, non-viral methods concentrate on targeted delivery to chondrocytes or MSCs for tissue engineering-based approaches. For the IVD, growth factors such as GDF5 or GDF6 or developmental transcription factors such as Brachyury or FOXF1 seem to be of high clinical interest. However, the most efficient method of gene transfer is still elusive, as several preclinical studies have reported many different non-viral methods and clinical translation of these techniques still needs to be validated. Here we discuss the non-viral methods applied for bone and joint and propose methods that can be promising in clinical use.

BMPR1A is necessary for chondrogenesis and osteogenesis, whereas BMPR1B prevents hypertrophic differentiation

BMP2 stimulates bone formation and signals preferably through BMP receptor (BMPR) 1A, whereas GDF5 is a cartilage inducer and signals preferably through BMPR1B. Consequently, BMPR1A and BMPR1B are believed to be involved in bone and cartilage formation, respectively. However, their function is not yet fully clarified. In this study, GDF5 mutants with a decreased affinity for BMPR1A were generated. These mutants, and wild-type GDF5 and BMP2, were tested for their ability to induce dimerization of BMPR1A or BMPR1B with BMPR2, and for their chondrogenic, hypertrophic and osteogenic properties in chondrocytes, in the multipotent mesenchymal precursor cell line C3H10T1/2 and the human osteosarcoma cell line Saos-2. Mutants with the lowest potency for inducing BMPR1A-BMPR2 dimerization exhibited minimal chondrogenic and osteogenic activities, indicating that BMPR1A is necessary for chondrogenic and osteogenic differentiation. BMP2, GDF5 and the GDF5 R399E mutant stimulated expression of chondrogenic and hypertrophy markers in C3H10T1/2 cells and chondrocytes. However, GDF5 R399E, which induces the dimerization of BMPR1B and BMPR2 more potently than GDF5 or BMP2, displayed reduced hypertrophic activity. Therefore, we postulate that stronger BMPR1B signaling, compared to BMPR1A signaling, prevents chondrocyte hypertrophy and acts as a cartilage stabilizer during joint morphogenesis.This article has an associated First Person interview with the first author of the paper.

GDF5 induces TBX3 in a concentration dependent manner - on a gold nanoparticle gradient

Organs and tissues, such as cartilage and limbs, are formed during development through an orchestration of growth factors that function as morphogens. Examples of growth factors include growth differentiation factor 5 (GDF5) and transforming growth factors beta 1 and 3 (TGFβ-1 and TGFβ-3) which can specify creation of more than one cell type after forming a concentration gradient in vivo. Here, we studied the impact of morphogen gradients during differentiation of induced pluripotent stem cells (iPSCs) into the chondrocyte lineage. Cell budding zones, consisting of condensed cell aggregates, were observed only in gradients of GDF5. T-box transcription factor 3 (TBX3) was detected specifically in the budding zones (ranging from 500-1,500 particles/μm2) of nuclei and cell vesicles. A homogenous density of GDF5 of 900 particles/μm2 on a surface induced budding and expression of TBX3 after five days in iPSCs. Therefore, we conclude that a gradient of GDF5, as well as the specific homogenous density of GDF5, support the induction of TBX3 in iPCSs. Moreover, differentiation of iPSCs first on GDF5 gradient or homogenous surfaces for five days and then in a three-dimensional structure for five weeks resulted in pellets that expressed TBX3.

Evolutionary Selection and Constraint on Human Knee Chondrocyte Regulation Impacts Osteoarthritis Risk

During human evolution, the knee adapted to the biomechanical demands of bipedalism by altering chondrocyte developmental programs. This adaptive process was likely not without deleterious consequences to health. Today, osteoarthritis occurs in 250 million people, with risk variants enriched in non-coding sequences near chondrocyte genes, loci that likely became optimized during knee evolution. We explore this relationship by epigenetically profiling joint chondrocytes, revealing ancient selection and recent constraint and drift on knee regulatory elements, which also overlap osteoarthritis variants that contribute to disease heritability by tending to modify constrained functional sequence. We propose a model whereby genetic violations to regulatory constraint, tolerated during knee development, lead to adult pathology. In support, we discover a causal enhancer variant (rs6060369) present in billions of people at a risk locus (GDF5-UQCC1), showing how it impacts mouse knee-shape and osteoarthritis. Overall, our methods link an evolutionarily novel aspect of human anatomy to its pathogenesis.

Complex Phenotypes: Mechanisms Underlying Variation in Human Stature

PURPOSE OF REVIEW

The goal of the review is to provide a comprehensive overview of the current understanding of the mechanisms underlying variation in human stature.

RECENT FINDINGS

Human height is an anthropometric trait that varies considerably within human populations as well as across the globe. Historically, much research focus was placed on understanding the biology of growth plate chondrocytes and how modifications to core chondrocyte proliferation and differentiation pathways potentially shaped height attainment in normal as well as pathological contexts. Recently, much progress has been made to improve our understanding regarding the mechanisms underlying the normal and pathological range of height variation within as well as between human populations, and today, it is understood to reflect complex interactions among a myriad of genetic, environmental, and evolutionary factors. Indeed, recent improvements in genetics (e.g., GWAS) and breakthroughs in functional genomics (e.g., whole exome sequencing, DNA methylation analysis, ATAC-sequencing, and CRISPR) have shed light on previously unknown pathways/mechanisms governing pathological and common height variation. Additionally, the use of an evolutionary perspective has also revealed important mechanisms that have shaped height variation across the planet. This review provides an overview of the current knowledge of the biological mechanisms underlying height variation by highlighting new research findings on skeletal growth control with an emphasis on previously unknown pathways/mechanisms influencing pathological and common height variation. In this context, this review also discusses how evolutionary forces likely shaped the genomic architecture of height across the globe.

In Vitro Release of Bioactive Bone Morphogenetic Proteins (GDF5, BB-1, and BMP-2) from a PLGA Fiber-Reinforced, Brushite-Forming Calcium Phosphate Cement

Bone regeneration of sheep lumbar osteopenia is promoted by targeted delivery of bone morphogenetic proteins (BMPs) via a biodegradable, brushite-forming calcium-phosphate-cement (CPC) with stabilizing poly(l-lactide-co-glycolide) acid (PLGA) fibers. The present study sought to quantify the release and bioactivity of BMPs from a specific own CPC formulation successfully used in previous in vivo studies. CPC solid bodies with PLGA fibers (0%, 5%, 10%) containing increasing dosages of GDF5, BB-1, and BMP-2 (2 to 1000 µg/mL) were ground and extracted in phosphate-buffered saline (PBS) or pure sheep serum/cell culture medium containing 10% fetal calf serum (FCS; up to 30/31 days). Released BMPs were quantified by ELISA, bioactivity was determined via alkaline phosphatase (ALP) activity after 3-day exposure of different osteogenic cell lines (C2C12; C2C12BRlb with overexpressed BMP-receptor-1b; MCHT-1/26; ATDC-5) and via the influence of the extracts on the expression of osteogenic/chondrogenic genes and proteins in human adipose tissue-derived mesenchymal stem cells (hASCs). There was hardly any BMP release in PBS, whereas in medium + FCS or sheep serum the cumulative release over 30/31 days was 11-34% for GDF5 and 6-17% for BB-1; the release of BMP-2 over 14 days was 25.7%. Addition of 10% PLGA fibers significantly augmented the 14-day release of GDF5 and BMP-2 (to 22.6% and 43.7%, respectively), but not of BB-1 (13.2%). All BMPs proved to be bioactive, as demonstrated by increased ALP activity in several cell lines, with partial enhancement by 10% PLGA fibers, and by a specific, early regulation of osteogenic/chondrogenic genes and proteins in hASCs. Between 10% and 45% of bioactive BMPs were released in vitro from CPC + PLGA fibers over a time period of 14 days, providing a basis for estimating and tailoring therapeutically effective doses for experimental and human in vivo studies.

DNA hypermethylation of GDF5 in developmental dysplasia of the hip (DDH)

Introduction & Objective

Developmental Dysplasia of the Hip (DDH) is one of the most common congenital skeletal anomalies. Body of evidence suggests that genetic variations in GDF5 are associated with susceptibility to DDH. DDH is a multifactorial disease and its etiology has not been entirely determined. Epigenetic changes such as DNA methylation could be linked to DDH. In this scheme, we hypothesized that changes in GDF5 DNA methylation could predispose a susceptible individual to DDH.

Methods

This study consisted of 45 DDH patients and 45 controls with healthy femoral neck cartilage, who underwent hemi‐, or total arthroplasty for the femoral neck fracture. A cartilage sample of 1 cm in diameter and 1 mm in the thickness was obtained for DNA extraction. DNA was extracted and DNA methylation of GDF5 was evaluated by metabisulfite method.

Results

Methylation analysis showed that the promoter of GDF5 in cartilage samples from DDH patients was hypermethylated in comparison to healthy controls (p = .001).

Conclusion

Our study showed that the methylation status of the GDF5 in patients with DDH is dysregulated. This dysregulation indicates that adjustment in the methylation might modify the expression of this gene. Since this gene plays an essential role in cartilage and bone development, thus reducing its expression can contribute to the pathogenesis of DDH. Further studies are needed to elucidate the role of GDF5 in this disease.

Interaction between GDF5 gene polymorphisms and environment factors increased the risk of knee osteoarthritis: a case-control study

Using a case–control design, we assessed the association between single nucleotide polymorphisms (SNPs) of growth and differentiation factor 5 (GDF5)/rs143383 gene and interaction with environments and knee osteoarthritis (KOA). We recruited 288 KOA patients from the First Clinical College, Henan University of Chinese Medicine between June 2017 and May 2018. There was significant difference in genotype distribution between case group and control group (χ² = 22.661, P=0.000). The minor C allele was significantly higher in the case group than that in the control group (20.5 vs 8.1%, P=0.000, odds ratio (OR) = 1.62, 95% confidence interval (CI): 1.29–2.03). Significant differences were also observed in other gene models. For age, all models show significant differences (P<0.05) for those whose age was more than 60 years, and no significant difference was observed for those under 60 years. For non-smoking group, there were significant differences between case group and control group, and for smoker, significance level was found in TT compared with CC and allele gene models. Patients with drinking and Bbody mass index (MI )≥ 24 also showed significant relationship between rs143383 and osteoarthritis (OA) under the following models: TT vs CC (P=0.000, P=0.018), TT/CT vs CC (P=0.043), TT vs CT/CC (P=0.000, P=0.009), and T vs C (P=0.024, P=0.000). Other gene models indicated no significance (P>0.05). Our results revealed a possible genetic association between GDF5 and KOA, and the TT genotype of rs143383 increased the risk of KOA in Chinese Han population. The interaction between GDF5 gene and drinking, smoking, and obesity further increased the risk of KOA.

Association between GDF5 single nucleotide polymorphism rs143383 and lumbar disc degeneration

The association between growth differentiation factor 5 (GDF5), single nucleotide polymorphism (SNP) rs143383 and lumbar disc degeneration (LDD) was investigated. A total of 210 patients with LDD (observation group) and 320 patients without lumbar diseases (control group) diagnosed in Shanghai General Hospital of Nanjing Medical University from August 2013 to March 2017 were randomly selected. Then, deoxyribonucleic acid (DNA) was extracted from the blood of each patient, and Taq-man fluorescent quantitative polymerase chain reaction (qPCR) technique was used to detect rs143383 in GFD5 gene. The frequency of different genotypes in observation group and control group was counted, and the associations between different SNP genotypes and the incidence of LDD were analyzed. Good genotyping results were found in both LDD patient group and control group. There were no significant differences in distribution frequency of TT and TC genotypes at site rs143383 between LDD patient group and control group (P>0.05), but the distribution frequency of CC genotype at site rs143383 in LDD patient group had a statistically significant difference from that in control group (P<0.05). In dominant models, odds ratio (OR) of (TC+CC/TT) was 1.195 (P=0.532). In recessive models, OR of (CC/TT+TC) was 4.333 (P=0.028). In co-dominant models, ORs of (TC/TT) and (CC/TT) were 0.967 and 4.43, respectively (P=0.99). The differences in 3 genotypes showed no statistical significance among different pathological grades (Grade I to V) (χ²=1.034, P=0.998), and there was no statistically significant difference in T and C (χ²=0.012, P=0.999). Pathological grades in dominant models, recessive models and over dominant models were analyzed, and no statistically significant difference was found (P>0.05). In conclusion, CC mutant type at rs143383 in GDF5 gene has a strong association with the incidence of LDD, and a high prevalence risk, but it has no evident correlation with pathological grades.

microRNA-665 promotes the proliferation and matrix degradation of nucleus pulposus through targeting GDF5 in intervertebral disc degeneration

Growing evidences suggested that microRNAs (miRNAs) played important roles in the development of intervertebral disc degeneration (IDD). However, the expression level and function of miR-665 in IDD remain unknown. In this study, we showed that the expression level of miR-665 was upregulated in degenerative human NP samples. In addition, miR-665 expression level gradually increased with the exacerbation of disc degeneration grade. Moreover, miR-665 expression level was positively associated with the Pfirrmann grade. Ectopic expression of miR-665 promoted NP cell growth. Furthermore, miR-665 overexpression decreased aggrecan and Col II expression and ectopic expression of miR-665 increased MMP-3 and MMP-13 expression in NP cell. We identified growth differentiation factor 5 (GDF5) was a direct target gene of miR-665 in NP cell and enforced expression of miR-665 decreased GDF5 expression. Elevated expression of miR-665 enhanced NP cell proliferation and decreased aggrecan and Col II expression. In addition, ectopic expression of miR-665 increased MMP-3 and MMP-13 expression through inhibiting GDF5 expression in NP cells. These results suggested that dysregulated miR-665 expression might act an important role in the development of IDD.

Extracellular matrix protein production in human adipose-derived mesenchymal stem cells on three-dimensional polycaprolactone (PCL) scaffolds responds to GDF5 or FGF2

Purpose

The poor healing potential of intra-articular ligament injuries drives a need for the development of novel, viable 'neo-ligament' alternatives. Ex vivo approaches combining stem cell engineering, 3-dimensional biocompatible scaffold design and enhancement of biological and biomechanical functionality via the introduction of key growth factors and morphogens, represent a promising solution to ligament regeneration.

Methods

We investigated growth, differentiation and extracellular matrix (ECM) protein production of human adipose-derived mesenchymal stem/stromal cells (MSCs), cultured in 5% human platelet lysate (PL) and seeded on three-dimensional polycaprolactone (PCL) scaffolds, in response to the connective-tissue related ligands fibroblast growth factor 2 (basic) (FGF2) and growth and differentiation factor-5 (GDF5). Phenotypic alterations of MSCs under different biological conditions were examined using cell viability assays, real time qPCR analysis of total RNA, as well as immunofluorescence microscopy.

Results

Phenotypic conversion of MSCs into ECM producing fibroblastic cells proceeds spontaneously in the presence of human platelet lysate. Administration of FGF2 and/or GDF5 enhances production of mRNAs for several ECM proteins including Collagen types I and III, as well as Tenomodulin (e.g., COL1A1, TNMD), but not Tenascin-C (TNC). Differences in the in situ deposition of ECM proteins Collagen type III and Tenascin-C were validated by immunofluorescence microscopy.

Summary

Treatment of MSCs with FGF2 and GDF5 was not synergistic and occasionally antagonistic for ECM production. Our results suggest that GDF5 alone enhances the conversion of MSCs to fibroblastic cells possessing a phenotype consistent with that of connective-tissue fibroblasts.

Knock-in human GDF5 proregion L373R mutation as a mouse model for proximal symphalangism

Proximal symphalangism (SYM1) is an autosomal dominant disorder, mainly characterized by bony fusions of the proximal phalanges of the hands and feet. GDF5 and NOG were identified to be responsible for SYM1. We have previously reported on a p.Leu373Arg mutation in the GDF5 proregion present in a Chinese family with SYM1. Here, we investigated the effects of the GDF-L373R mutation. The variant caused proteolysis efficiency of GDF5 increased in ATDC5 cells. The variant also caused upregulation of SMAD1/5/8 phosphorylation and increased expression of target genes SMURF1, along with COL2A1 and SOX9 which are factors associated with chondrosis. Furthermore, we developed a human-relevant SYM1 mouse model by making a Gdf5^L367R (the orthologous position for L373R in humans) knock-in mouse. Gdf5^L367R/+ and Gdf5^L367R/L367R mice displayed stiffness and adhesions across the proximal phalanx joint which were in complete accord with SYM1. It was also confirmed the joint formation and development was abnormal in Gdf5^L367R/+ and Gdf5^L367R/L367R mice, including the failure to develop the primary ossification center and be hypertrophic chondrocytes during embryonic development. This knock-in mouse model offers a tool for assessing the pathogenesis of SYM1 and the function of the GDF5 proregion.

Chimerism for 20q11.2 microdeletion of GDF5 explains discordant phenotypes in monochorionic-diamniotic twins

Microdeletions of 20q11.2 are rare but have been associated with characteristic clinical findings. A 1.6 Mb minimal critical region has been identified that includes three OMIM genes: GDF5, EPB41L1, and SAMHD. Here we describe a male monozygotic, monochorionic-diamniotic twin pair with discordant phenotypes, one with multiple findings that overlap with those reported in 20q11.2 deletions, and the other unaffected. Microarray analysis revealed mosaicism for a 363 Kb deletion encompassing GDF5 in the peripheral blood of both twins, which was confirmed by FISH. Subsequent FISH on buccal cells identified the deletion only in the affected twin. The blood FISH findings were interpreted as representing chimerism resulting from anastomosis and the blood exchange between the twins in utero. The implications of this finding are discussed, as is the contribution of GDF5 to the associated clinical findings of 20q11.2 deletions.

The Good the Bad and the Ugly of Glycosaminoglycans in Tissue Engineering Applications

High sulfation, low cost, and the status of heparin as an already FDA- and EMA- approved product, mean that its inclusion in tissue engineering (TE) strategies is becoming increasingly popular. However, the use of heparin may represent a naïve approach. This is because tissue formation is a highly orchestrated process, involving the temporal expression of numerous growth factors and complex signaling networks. While heparin may enhance the retention and activity of certain growth factors under particular conditions, its binding 'promiscuity' means that it may also inhibit other factors that, for example, play an important role in tissue maintenance and repair. Within this review we focus on articular cartilage, highlighting the complexities and highly regulated processes that are involved in its formation, and the challenges that exist in trying to effectively engineer this tissue. Here we discuss the opportunities that glycosaminoglycans (GAGs) may provide in advancing this important area of regenerative medicine, placing emphasis on the need to move away from the common use of heparin, and instead focus research towards the utility of specific GAG preparations that are able to modulate the activity of growth factors in a more controlled and defined manner, with less off-target effects.

Intra-articular therapy with recombinant human GDF5 arrests disease progression and stimulates cartilage repair in the rat medial meniscus transection (MMT) model of osteoarthritis

OBJECTIVE

Investigation of osteoarthritis (OA) risk alleles suggests that reduced levels of growth and differentiation factor-5 (GDF5) may be a precipitating factor in OA. We hypothesized that intra-articular recombinant human GDF5 (rhGDF5) supplementation to the OA joint may alter disease progression.

METHODS

A rat medial meniscus transection (MMT) joint instability OA model was used. Animals received either one intra-articular injection, or two or three bi-weekly intra-articular injections of either 30 μg or 100 μg of rhGDF5 beginning on day 21 post surgery after structural pathology had been established. Nine weeks after MMT surgery, joints were processed for histological analysis following staining with toluidine blue. Control groups received intra-articular vehicle injections, comprising a glycine-buffered trehalose solution. OA changes in the joint were evaluated using histopathological end points that were collected by a pathologist who was blinded to treatment.

RESULTS

Intra-articular rhGDF5 supplementation reduced cartilage lesions on the medial tibial plateau in a dose-dependent manner when administered therapeutically to intercept OA disease progression. A single 100 μg rhGDF5 injection on day 21 slowed disease progression at day 63. A similar effect was achieved with two bi-weekly injections of 30 μg. Two bi-weekly injections of 100 μg or three bi-weekly injections of 30 μg stopped progression of cartilage lesions. Importantly, three biweekly injections of 100 μg rhGDF5 stimulated significant cartilage repair.

CONCLUSIONS

Intra-articular rhGDF5 supplementation can prevent and even reverse OA disease progression in the rat MMT OA model. Collectively, these results support rhGDF5 supplementation as an intra-articular disease modifying OA therapy.

Severe Form of Brachydactyly Type A1 in a Child with a c.298G > A Mutation in IHH Gene

Brachydactyly type A1 (BDA1) is characterized by short middle phalanges. We report the case of a child with a severe form of BDA1 with complete absence of the middle phalanges of all extremities. He had c.298G > A (p.D100N) mutation in IHH gene.

Association between GDF5 +104T/C polymorphism and knee osteoarthritis in Caucasian and Asian populations: a meta-analysis based on case-control studies

Background

Osteoarthritis (OA) is a degenerative joint disease with a complex genetic background. Variants in growth differentiation factor 5 (GDF5) have been reported to be associated with rheumatoid arthritis (RA) in several ethnic populations. The present study aimed to assess the association between the GDF5 +104T/C polymorphism and the susceptibility of the knee to OA through a meta-analysis of available case-control studies.

Methods

The PubMed and Science Direct citation databases were used to search electronic literature in order to identify studies published between January 2007 and July 2016 that evaluated the association between the GDF5 +104T/C polymorphism and the susceptibility of the knee to OA. Different genetic models were used to assess the pooled and stratified data.

Results

A positive association was found in all pooled studies (OR = 0.808, 95 % CI = 0.754–0.866, p < 0.001). Regarding genotypes, significant associations were found using a dominant model (OR = 0.777, 95 % CI = 0.708–0.852, p < 0.001), a recessive model (OR = 0.723, 95%CI = 0.623–0.839, p < 0.001), and an additive model (CC vs TT OR = 0.648, 95 % CI = 0.552–0.760, p < 0.001; CC vs CT OR = 0.801, 95 % CI = 0.685–0.936, p = 0.005). Meta-analysis data were stratified by ethnicity, and the GDF5 C allele was found to be positively associated with OA of the knee in both Caucasians and Asians, as were the GDF5 TC and CC genotypes. In addition, using an additive model, the CC genotype was found to be significantly associated with OA of the knee in both Caucasians and Asians when comparing CC vs TT genotypes, but not in Caucasians when comparing TT vs CT genotypes.

Conclusions

Meta-analysis results indicated that the GDF5 +104T/C polymorphism is a protective factor for OA among Caucasian and Asian populations.

MiR-132-3p Regulates the Osteogenic Differentiation of Thoracic Ligamentum Flavum Cells by Inhibiting Multiple Osteogenesis-Related Genes

Ossification of the ligamentum flavum (OLF) is a disorder of heterotopic ossification of spinal ligaments and is the main cause of thoracic spinal canal stenosis. Previous studies suggested that miR-132-3p negatively regulates osteoblast differentiation. However, whether miR-132-3p is involved in the process of OLF has not been investigated. In this study, we investigated the effect of miR-132-3p and its target genes forkhead box O1 (FOXO1), growth differentiation factor 5 (GDF5) and SRY-box 6 (SOX6) on the osteogenic differentiation of ligamentum flavum (LF) cells. We demonstrated that miR-132-3p was down-regulated during the osteogenic differentiation of LF cells and negatively regulated the osteoblast differentiation. Further, miR-132-3p targeted FOXO1, GDF5 and SOX6 and down-regulated the protein expression of these genes. Meanwhile, FOXO1, GDF5 and SOX6 were up-regulated after osteogenic differentiation and the down-regulation of endogenous FOXO1, GDF5 or SOX6 suppressed the osteogenic differentiation of LF cells. In addition, we also found FOXO1, GDF5 and SOX6 expression in the ossification front of OLF samples. Overall, these results suggest that miR-132-3p inhibits the osteogenic differentiation of LF cells by targeting FOXO1, GDF5 and SOX6.

Protection of cultured dopamine neurons from MPP(+) requires a combination of neurotrophic factors

Parkinson's disease is a progressive neurodegenerative disorder, caused in part by the loss of dopamine (DA) neurons in the substantia nigra (SN). Neurotrophic factors have been shown to increase the basal survival of DA neurons in vitro, as well as to protect the neurons from some toxins under certain in vitro conditions and in animal models. Although these factors have often been tested individually, they have rarely been studied in combinations. We therefore examined the effect of such combinations after acute exposure to the toxin 1-methyl-4-phenylpyridinium (MPP(+) ) using dissociated postnatal rat midbrain cultures isolated from SN and ventral tegmental area (VTA). We found that significant loss of DA neurons in the SN occurred with an LC50 of between 1 and 10 μm, whereas the LC50 of DA neurons from the VTA was approximately 1000-fold higher. We did not observe neuroprotection against MPP(+) by individual exposure to glial cell-line derived neurotrophic factor (GDNF), brain derived neurotrophic factor (BDNF), transforming growth factor beta (TGFβ), basic fibroblast growth factor (FGF-2) or growth/differentiation factor 5 (GDF5) at concentrations of 100 or 500 ng/mL. Combinations of two, three or four neurotrophic factors were also ineffective. However, when the SN cultures were exposed to a combination of all five neurotrophic factors, each at a concentration of 100 ng/mL, we observed a 30% increase in DA neuron survival in the presence of 10 and 500 μm MPP(+) . These results may be relevant to the use of neurotrophic factors as therapeutic treatments for Parkinson's disease.

Genetic Contribution to the Development of Radiographic Knee Osteoarthritis in a Population Presenting with Nonacute Knee Symptoms a Decade Earlier

This study examined the contribution of the osteoarthritis (OA) susceptibility genes ASPN, GDF5, DIO2, and the 7q22 region to the development of radiographic knee OA in patients with a mean age of 40.6 ± 7.9 years (standard deviation) and who suffered from nonacute knee complaints a decade earlier. Dose–response associations of four single nucleotide polymorphisms(SNPs) in the susceptibility genes were determined by comparing 36 patients who showed the development of OA on radiographs (Kellgren and Lawrence score ≥1) with 88 patients having normal cartilage with no development of OA on radiographs. Multivariate logistic regression analysis including the variables such as age, gender, body mass index, and reported knee trauma was performed. A dose–response association of DIO2 SNP rs225014: odds ratio (OR) 2.3, 95% confidence interval (CI) 1.1–4.5 (P = 0.019) and GDF5 SNP rs143383: OR 2.0, 95% CI 1.1–3.8 (P = 0.031) was observed with knee OA development. The ASPN and 7q22 SNPs were not associated with OA development.

Recurrent mutation in CDMP1 in a family with Grebe chondrodysplasia: broadening the phenotypic manifestation of syndrome in Pakistani population

Grebe syndrome (OMIM-200700) is a very rare type of acromesomelic dysplasia with autosomal recessive inheritance. We studied a Pakistani family with two affected individuals having typical features of Grebe chondrodysplasia. Patients were observed with short and deformed limbs having a proximo-distal gradient of severity. Hind-limbs were more severely affected than fore-limbs. Digits on autopods were very short and nonfunctional. Index subject also had nearsightedness. However, symptoms in the craniofacial and axial skeleton were minimal. Genetic analysis revealed four base pair insertion mutation (c.1114insGAGT) in gene coding cartilage-derived morphogenetic protein-1 (CDMP1). This mutation was predicted to cause premature stop codon. The clinical presentation in this study broadens the range of phenotypes associated with CDMP1 mutation in Pakistani population.

Gdf5 progenitors give rise to fibrocartilage cells that mineralize via hedgehog signaling to form the zonal enthesis

The sequence of events that leads to the formation of a functionally graded enthesis is not clearly defined. The current study demonstrates that clonal expansion of Gdf5 progenitors contributes to linear growth of the enthesis. Prior to mineralization, Col1+ cells in the enthesis appose Col2+ cells of the underlying primary cartilage. At the onset of enthesis mineralization, cells at the base of the enthesis express alkaline phosphatase, Indian hedgehog, and ColX as they mineralize. The mineralization front then extends towards the tendon midsubstance as cells above the front become encapsulated in mineralized fibrocartilage over time. The hedgehog (Hh) pathway regulates this process, as Hh-responsive Gli1+ cells within the developing enthesis mature from unmineralized to mineralized fibrochondrocytes in response to activated signaling. Hh signaling is required for mineralization, as tissue-specific deletion of its obligate transducer Smoothened in the developing tendon and enthesis cells leads to significant reductions in the apposition of mineralized fibrocartilage. Together, these findings provide a spatiotemporal map of events - from expansion of the embryonic progenitor pool to synthesis of the collagen template and finally mineralization of this template - that leads to the formation of the mature zonal enthesis. These results can inform future tendon-to-bone repair strategies to create a mechanically functional enthesis in which tendon collagen fibers are anchored to bone through mineralized fibrocartilage.

Growth without growth hormone: can growth and differentiation factor 5 be the mediator?

Growth without growth hormone (GH) is often observed in the setup of obesity; however, the missing link between adipocytes and linear growth was until now not identified. 3T3L1 cells were induced to differentiate into adipocytes and their conditioned medium (CM) (adipocytes CM, CMA) was added to metatarsals bone culture and compared to CM derived from undifferentiated cells. CMA significantly increased metatarsals bone elongation. Adipogenic differentiation increased the expression of growth and differentiation factor (GDF)-5, also found to be secreted into the CMA. GDF-5 significantly increased metatarsal length in culture; treatment of the CMA with anti-GDF-5 antibody significantly reduced the stimulatory effect on bone length. The presence of GDF-5 receptor (bone morphogenetic protein receptor; BMPR1) in metatarsal bone was confirmed by immunohistochemistry. Animal studies in rodents subjected to food restriction followed by re-feeding showed an increase in GDF-5 serum levels concomitant with nutritional induced catch up growth. These results show that adipocytes may stimulate bone growth and suggest an additional explanation to the growth without GH phenomenon.

Novel indel Mutation in the GDF5 Gene Is Associated with Brachydactyly Type C in a Four-Generation Turkish Family

Heterozygous loss-of-function mutations of GDF5 are reported to cause hypoplasia/aplasia of certain skeletal elements (brachydactyly), and heterozygous gain-of-function mutations, occurring either on the gene itself or through the loss of its inhibitor noggin, result in joint fusion (symphalangism). We present here the clinical and molecular investigation of a family with disproportionate shortness of the second and third fingers which comprises 9 variably affected members spanning 4 generations. In this study, we performed clinical and radiographical examinations of 2 patients of this family, sequencing of GDF5 and 3D protein modeling of the wildtype and mutated polypeptide to predict the structural alteration. Diagnoses were compatible with familial brachydactyly type C. GDF5 analysis revealed a novel heterozygous in-frame indel mutation (c.803_ 827del25ins25), involving the propeptide domain of GDF5 that alters the number of random coil and beta-strand structures, creating a 1-turn-helix at the mutated site. The mutation described here is the second indel reported in GDF5. The previously published homozygous indel mutation affected the TGF-beta like domain and was associated with Du Pan syndrome. The novel mutation reported here presents further allelic heterogeneity and a probable intrafamilial variable clinical expressivity of GDF5.

6-Hydroxydopamine induces distinct alterations in GDF5 and GDNF mRNA expression in the rat nigrostriatal system in vivo

Growth/differentiation factor (GDF)5 and glial cell line-derived neurotrophic factor (GDNF) are neurotrophic factors that promote the survival of midbrain dopaminergic neurons in vitro and in vivo. Both factors have potent neurotrophic and neuroprotective effects in rat models of Parkinson's disease (PD) and represent promising new therapies for PD. The aim of this study was to investigate the expression of GDF5, GDNF and their receptors in the nigrostriatal dopaminergic system in rat models of PD. It found that endogenous GDF5, GDNF and their receptors are differentially expressed in two 6-hydroxydopamine lesion models of PD. In both striatal and medial forebrain bundle (MFB) lesion models, striatal levels of GDF5 mRNA increased at 10 days post-lesion, while GDNF mRNA levels in the nigrostriatal system decreased after 10 and 28 days. Midbrain mRNA levels for both GDF5 receptors transiently increased after striatal lesion, whereas those of two GDNF receptors decreased at later time-points in both models. Despite the fact that exogenous GDF5 and GDNF have comparable effects on dopaminergic neurons in vitro and in vivo, their endogenous responses to neurotoxic injury are different. This highlights the importance of studying neurotrophic factor expression at distinct disease stages and in various animal models of PD.

A modified aggregate culture for chondrogenesis of human adipose-derived stem cells genetically modified with growth and differentiation factor 5

Adipose-derived stem cells (ADSCs) are an attractive cell source for tissue engineering, and recently a modified aggregate culture of human ADSCs (hADSCs) was established based on preparation of three-dimensional (3D) cell aggregates in growth factor–enriched low serum medium using the hanging droplet method. Growth and differentiation factor 5 (GDF5) plays a critical role in chondrogenesis and cartilage development. In the present study, we examine (1) whether the modified aggregate culture is feasible for chondrogenic induction of hADSCs, (2) whether overexpressed GDF5 can promote chondrogenesis, and (3) the gene expression profile during chondrogenesis in this aggregate culture. hADSCs were infected with an adenovirus carrying the GDF5 gene (Ad-GDF5). Cells were cultured with chondrogenic media either in a modified aggregate culture or in an attached micromass culture that served as a control. The chondrogenic phenotype was assessed by morphology (n=8), biochemistry (n=3), and histology (n=2). Expression of 12 genes was determined by quantitative real-time polymerase chain reaction (n=3). We found that ADSCs cultured in the modified aggregates exhibited denser pellets and higher content of sulfated glycosaminoglycan (sGAG) compared with those cultured in the micromass. Infection of cells with Ad-GDF5 increased the aggregate size and sGAG content. It also up-regulated expression of GDF5, aggrecan, and leptin and down-regulated expression of COL I, while expression of COL II and COL 10 remained unchanged. We concluded that the modified aggregate culture is feasible for chondrogenic induction of human ADSCs. Infection with Ad-GDF5 appears to promote the chondrogenesis. These findings suggest that genetic modification of ADSCs with GDF5 in the modified aggregate culture could be useful for treating diseases with cartilage defects.

BMP2 and GDF5 induce neuronal differentiation through a Smad dependant pathway in a model of human midbrain dopaminergic neurons

Parkinson's disease is the second most common neurodegenerative disease, and is characterised by the progressive degeneration of the nigrostriatal dopaminergic (DA) system. Current treatments are symptomatic, and do not protect against the DA neuronal loss. One of the most promising treatment approaches is the application of neurotrophic factors to rescue the remaining population of nigrostriatal DA neurons. Therefore, the identification of new neurotrophic factors for midbrain DA neurons, and the subsequent elucidation of the molecular bases of their effects, are important. Two related members of the bone morphogenetic protein (BMP) family, BMP2 and growth differentiation factor 5 (GDF5), have been shown to have neurotrophic effects on midbrain DA neurons both in vitro and in vivo. However, the molecular (signalling pathway(s)) and cellular (direct neuronal or indirect via glial cells) mechanisms of their effects remain to be elucidated. Using the SH-SH5Y human neuronal cell line, as a model of human midbrain DA neurons, we have shown that GDF5 and BMP2 induce neurite outgrowth via a direct mechanism. Furthermore, we demonstrate that these effects are dependent on BMP type I receptor activation of canonical Smad 1/5/8 signalling.

Rs143383 in the growth differentiation factor 5 (GDF5) gene significantly associated with osteoarthritis (OA)-a comprehensive meta-analysis

Family, twin, adoption studies show osteoarthritis (OA) has a substantial genetic component. Several studies have shown an association between OA and Growth Differentiation Factor 5 (GDF5), some others have not. Thus, the status of the OA-GDF5 association is uncertain. This meta-analysis was applied to case-control studies of the association between OA and GDF5 to assess the joint evidence for the association, the influence of individual studies, and evidence for publication bias. Relevant studies were identified from the following electronic databases: MEDLINE and current contents before Feb. 2012. For the case-control studies, the authors found 1) support for the association between OA and GDF5. The rs143383 polymorphism was significantly associated with OA [fixed: OR and 95% CI: 1.193 (1.139-1.249), p < 0.001; random: OR and 95% CI: 1.204 (1.135-1.276), p < 0.001], 2) no evidence that this association was accounted for by any one study, and 3) no evidence for publication bias. Although the effect size of the association between OA and GDF5 is small, there is suggestive evidence for an association. Further studies are needed to clarify what variant of GDF5 (or some nearby gene) accounts for this association.