Expression of growth differentiation factor 6 in the human developing fetal spine retreats from vertebral ossifying regions and is restricted to cartilaginous tissues

Abstract

During embryogenesis vertebral segmentation is initiated by sclerotomal cell migration and condensation around the notochord, forming anlagen of vertebral bodies and intervertebral discs. The factors that govern the segmentation are not clear. Previous research demonstrated that mutations in growth differentiation factor 6 resulted in congenital vertebral fusion, suggesting this factor plays a role in development of vertebral column. In this study, we detected expression and localization of growth differentiation factor 6 in human fetal spinal column, especially in the period of early ossification of vertebrae and the developing intervertebral discs. The extracellular matrix proteins were also examined. Results showed that high levels of growth differentiation factor 6 were expressed in the nucleus pulposus of intervertebral discs and the hypertrophic chondrocytes adjacent to the ossification centre in vertebral bodies, where strong expression of proteoglycan and collagens was also detected. As fetal age increased, the expression of growth differentiation factor 6 was decreased correspondingly with the progress of ossification in vertebral bodies and restricted to cartilaginous regions. This expression pattern and the genetic link to vertebral fusion suggest that growth differentiation factor 6 may play an important role in suppression of ossification to ensure proper vertebral segmentation during spinal development.

Therapeutic potential of growth differentiation factors in the treatment of degenerative disc diseases

“…During development, cellular secretion of GDFs forms directional morphogenetic gradients . Recently, the expression and localization of GDF6 in developing spinal column of human fetus have been examined . The strong expression of GDF6 is especially shown throughout cartilaginous region of vertebrae at early developing period (8‐13 weeks of gestation) and in the developing IVDs (between 8 and 19 weeks of gestation) and is diminished from ossification areas.…”

“…These could include cellular and acellular therapies delivered with and without instructive biomaterials and in conjunction with bioactive molecules or growth factors (see for recent in‐depth review). One such family of factors, growth differentiation factors (GDFs), appear to be an exciting prospect due to their crucial role in chondrogenesis (including differentiation to NP cells, namely, discogenesis) and cartilaginous tissue homeostasis . As such, the focus of this review is directed on the continuing development of regenerative strategies for IVD repair employing GDF family members and the potential therapeutic role of GDF6.…”

Microparticles for controlled growth differentiation factor 6 delivery to direct adipose stem cell‐based nucleus pulposus regeneration

“…Therapeutic regeneration strategies aim to abrogate this proinflammatory, catabolic positive feedback loop through the implantation of healthy cells and/or signalling molecules to instruct correct ECM production, particularly in the NP. One growth factor recently proposed for NP regeneration is growth differentiation factor 6 (GDF6), a member of the bone morphogenetic protein (BMP) family that plays important developmental roles in the formation of cartilaginous tissues, including the IVD (Clendenning & Mortlock, 2012;Settle et al, 2003;Tassabehji et al, 2008;Wei et al, 2016). GDF6 expression has been linked to anti-ageing effects in multiple tissues (Hisamatsu, Ohno-Oishi, Nakamura, Mabuchi, & Naka-Kaneda, 2016) and, whereas studies conducted in our laboratory and others do not suggest GDF6 expression decreases with degeneration (Gulati, Chung, Wei, & Diwan, 2015; Le Maitre, Freemont, & Hoyland, 2009), preclinical studies have demonstrated that injection of GDF6 into experimentally induced rabbit and ovine annular puncture models attenuates pro-inflammatory molecular changes and prevents progression of IVD degeneration (Miyazaki et al, 2018;Shen et al, 2009).…”

Cartilage Derived Morphogenetic Protein-2 Induces Cell Migration and Its Chondrogenic Potential in C28/I2 Cells

“…34,35 Collagen X is also expressed at endochondral ossification, by hypertrophic chondrocytes. 36 Interestingly, we have found strong CDMP-2 expression in hypertrophic chondrocytes in foetal spinal tissue, 37 and its expression has been linked with the delineation of bone boundaries in developing organisms. 28,29 Further studies are needed to determine the specific signaling pathway of CDMP-2 in regulating expression of specific extracellular matrix molecules both during development and in adult tissue maintenance, but the tendency for CDMP-2 to promote chondrogenic tissue renewal is encouraging from the perspective of therapeutic use in disc regeneration.…”