Developmentally inspired programming of adult human mesenchymal stromal cells toward stable chondrogenesis

Abstract

It is generally accepted that adult human bone marrow-derived mesenchymal stromal cells (hMSCs) are default committed toward osteogenesis. Even when induced to chondrogenesis, hMSCs typically form hypertrophic cartilage that undergoes endochondral ossification. Because embryonic mesenchyme is obviously competent to generate phenotypically stable cartilage, it is questioned whether there is a correspondence between mesenchymal progenitor compartments during development and in adulthood. Here we tested whether forcing specific early events of articular cartilage development can program hMSC fate toward stable chondrogenesis. Inspired by recent findings that spatial restriction of bone morphogenetic protein (BMP) signaling guides embryonic progenitors toward articular cartilage formation, we hypothesized that selective inhibition of BMP drives the phenotypic stability of hMSC-derived chondrocytes. Two BMP type I receptor-biased kinase inhibitors were screened in a microfluidic platform for their time- and dose-dependent effect on hMSC chondrogenesis. The different receptor selectivity profile of tested compounds allowed demonstration that transient blockade of both ALK2 and ALK3 receptors, while permissive to hMSC cartilage formation, is necessary and sufficient to maintain a stable chondrocyte phenotype. Remarkably, even upon compound removal, hMSCs were no longer competent to undergo hypertrophy in vitro and endochondral ossification in vivo, indicating the onset of a constitutive change. Our findings demonstrate that adult hMSCs effectively share properties of embryonic mesenchyme in the formation of transient but also of stable cartilage. This opens potential pharmacological strategies to articular cartilage regeneration and more broadly indicates the relevance of developmentally inspired protocols to control the fate of adult progenitor cell systems.

Chitosan‐based scaffold counteracts hypertrophic and fibrotic markers in chondrogenic differentiated mesenchymal stromal cells

“…This combination contributed to guide hBM‐MSCs chondrogenic differentiation by creating environmental conditions that contributed to recapitulate specific phases of chondrogenic differentiation, as also shown at the electron microscopy level. In line with our data, Occhetta et al () demonstrated that selective inhibition of bone morphogenic protein signaling was able to guide phenotypic stability of hMSC‐derived chondrocytes, confirming the importance of controlling the fate of adult progenitor cell system. TGFβ3 alone was not sufficient to well recapitulate hBM‐MSCs chondrogenic differentiation until Day 48, both collagen type 10 and collagen type 1 were not down modulated.…”

“…The fastest stress relaxation of hydrogels with First, we demonstrated that it was necessary to use a higher concentration of hBM-MSCs for obtaining their chondrogenic differentiation. In fact, by only using 10 6 hBM-MSCs, it was possible to reach a cell condensation necessary to promote their chondrogenic differentiation, as also reported by other studies (Agrawal et al, 2018;Liou, Rothrauff, Alexander, & Tuan, 2018;Occhetta et al, 2018). Moreover, we also evidenced that in static condition, a longer time point (Day 48) was necessary to obtain a scaffold completely filled both outside and inside.…”

“…In particular, we did not evidence modulation of typical chondrogenic markers, SOX9, collagen type 2, and aggrecan; however, we found that the hypertrophic (collagen type 10) and fibrotic MSCs commitment, as previously demonstrated by blocking bone morphogenic protein receptors (Occhetta et al, 2018).…”

“…TGFβ3 alone was not sufficient to well recapitulate hBM‐MSCs chondrogenic differentiation until Day 48, both collagen type 10 and collagen type 1 were not down modulated. The down‐modulation of both hypertrophic and fibrotic markers, which occurred only when high CH concentrations (16%) and TGFβ3 were contemporarily present, is certainly an important feature in determining hBM‐MSCs commitment, as previously demonstrated by blocking bone morphogenic protein receptors (Occhetta et al, ).…”

Micro-pellet culture reveals that bone marrow mesenchymal stromal cell (BMSC) chondrogenic induction is triggered by a single day of TGF-β1 exposure

“…Increasingly, the propensity of BMSCs to form hypertrophic tissue has been acknowledged as a barrier to successful clinical translation [1], and this has become an area of active research. Studies have reported successful obstruction of hypertrophy and formation of stable articular cartilage-like tissue by: (1) manipulation of WNT signalling [30,31]; (2) silencing of BMP receptor signalling via a proprietary molecule [32]; (3) provision of different soluble factors on opposite sides of a cartilage-like disc to replicate an osteochondral interface [33]; or (4) use of novel scaffolds [34]. While promising, a recent article critically notes that these studies have yet to be replicated by independent groups [35].…”