Regeneration of Jaw Joint Cartilage in Adult Zebrafish

Abstract

The poor intrinsic repair capacity of mammalian joint cartilage likely contributes to the high incidence of arthritis worldwide. Adult zebrafish can regenerate many structures that show limited or no healing capacity in mammals, including the jawbone. To test whether zebrafish can also regenerate damaged joints, we developed a surgical injury model in which the zebrafish jaw joint is destabilized via transection of the major jaw joint ligament, the interopercular–mandibular (IOM). Unilateral transection of the IOM ligament in 1-year-old fish resulted in an initial reduction of jaw joint cartilage by 14 days, with full regeneration of joint cartilage by 28 days. Joint cartilage regeneration involves the re-entry of articular chondrocytes into the cell cycle and the upregulated expression of sox10, a marker of developing chondrocytes in the embryo that becomes restricted to a subset of joint chondrocytes in adults. Genetic ablation of these sox10-expressing chondrocytes shows that they are essential for joint cartilage regeneration. To uncover the potential source of new chondrocytes during joint regeneration, we performed single-cell RNA sequencing of the uninjured adult jaw joint and identified multiple skeletal, connective tissue, and fibroblast subtypes. In particular, we uncovered a joint-specific periosteal population expressing coch and grem1a, with the jaw joint chondrocytes marked by grem1a expression during regeneration. Our findings demonstrate the capacity of zebrafish to regenerate adult joint cartilage and identify candidate cell types that can be tested for their roles in regenerative response.

Ligament injury in adult zebrafish triggers ECM remodeling and cell dedifferentiation for scar-free regeneration

“…Re-clustering of the two neural crest-derived superclusters revealed clusters of osteoblasts ( ifitm5 +), chondrocytes ( col2a1a +), superficial chondrocytes and synoviocytes ( prg4b +), ligamentocytes ( scxa +, thbs4a +), two types of dermal fibroblasts ( pah +), periosteal cells ( mmel1 +), three types of stromal cells (defined by either cxcl12a, coch , or col5a3a ), and glial cells ( mbpa+ ) 18,24 (Fig. 4a-c, Fig.…”

“…Interopercular-mandibular (IOM) ligament transection surgery was adapted from Smeeton et al, 2022 18 . Briefly, adult zebrafish were anesthetized with Tricaine MS-222 and restrained in a damp sponge.…”

“…However, while these models interrogate scar-free tendon regeneration in the context of development, there are currently no models to study scar-free ligament regeneration in mature adult ligaments. To address this need, we utilized the highly regenerative zebrafish as they are a well-established model for heart, spinal cord, and tail fin regeneration [13][14][15] and moreover possess regenerative synovial joints supported by ligaments [16][17][18] .…”

Cartilage regeneration in zebrafish depends on Nrg1/ErbB signaling pathway

“…The Tg(sox10:GFP) line labels the migrating neural crest cells (NCC) at early embryonic stages ( Dutton et al, 2008 ). Expression of GFP is reactivated from 48hpf in the differentiating chondrocytes of the jaw, which are NCC cranial skeletal derivatives, and this expression persists for several days ( Dutton et al, 2008 ; Paul et al, 2016 ; Giovannone et al, 2019 ; Smeeton et al, 2021 ). A previous study has determined that distinct populations of chondrocytes can be classified by their relative expression of col2a1:mCherry and sox10:GFP transgenes.…”

A single-cell transcriptional atlas reveals resident progenitor cell niche functions in TMJ disc development and injury

“…Recently, many works have investigated different fibrocartilage and hyaline cartilage tissues by using single-cell analyses [12][13][14][15][16] . Understanding these tissues at the single-cell level can provide insights into the onset and progression of pathology.…”