Biomimetic strategy for cartilage formation: synergy of stem cell micro-aggregates and supramolecular peptide nanofibers

Recapitulation of embryonic developmental events is receiving increasing recognition as a strategy to induce robust tissue regeneration. In this work, we aimed to explore the critical events of cartilage formation by combining adult human bone marrow-derived mesenchymal stromal cells (hBMSCs) with supramolecular nanofibrous hydrogel. The micro-aggregation led to the altered global transcriptional profiles of hBMSCs and enhanced chondrogenic commitment early in 24h. Furthermore, the supramolecular nanofiber structure formed by peptide amphiphiles (PAs) maintained the cell cohesion and favored the deposition of cartilaginous matrix, thus facilitating the progression of differentiation. Upon subcutaneous implantation, the hBMSCs microaggregates-laden PA hydrogel demonstrated evident ectopic cartilage formation. Notably, RNA-sequencing data illustrated that the PA hydrogel facilitated the in vivo chondrogenesis progression of the encapsulated donor cells, and also activated the chondrogenesis in the host tissue via paracrine signaling. We conclude that PA hydrogel delivering microaggregates of hBMSCs could recapitulate the critical developmental events during cartilage development. This bioinspired approach will offer the potential to regenerate functional and durable tissues for the functional recovery of traumatic injuries of the cartilaginous skeleton . Microaggregation of hBMSCs was induced by using in-house designed micro-well culture system and the obtained hBMSCs aggregates (3D) were cultured in vitro for 72hrs either in proliferation media or chondrogenic differentiation media. The same density of hBMSCs cultured in monolayer (2D) was set-up as control. 2000 microaggregates were harvested after 12, 24 and 72hrs to extract RNA for RNA sequencing. For in vivo samples, hBMSCs were loaded with or without supramolecular peptide amphiphles (PA) hydrogel and cultured for 3weeks in vitro in chondrogenic media before subcutaneous implantation in immunodeficient mice. After 1 week,explants (n=3) were harvested, total RNA was extracted, and RNA sequencing was performed.