Three-dimensional self-assembling nanofiber matrix rejuvenates aged/degenerative human tendon stem/progenitor cells

The poor healing capacity of tendons is known to worsen in the elderly. During tendon aging and degeneration,

endogenous human tendon stem/progenitor cells (hTSPCs) experience profound pathological changes. Here, we

explored a rejuvenation strategy for hTSPCs derived from aged/degenerated Achilles tendons (A-TSPCs) by

providing three-dimensional (3D) nanofiber hydrogels and comparing them to young/healthy TSPCs (Y-TSPCs).

RADA peptide hydrogel has a self-assembling ability, forms a nanofibrous 3D niche and can be further functionalized

by adding RGD motifs. Cell survival, apoptosis, and proliferation assays demonstrated that RADA and

RADA/RGD hydrogels support A-TSPCs in a comparable manner to Y-TSPCs. Moreover, they rejuvenated ATSPCs

to a phenotype similar to that of Y-TSPCs, as evidenced by restored cell morphology and cytoskeletal

architecture. Transmission electron, confocal laser scanning and atomic force microscopies demonstrated

comparable ultrastructure, surface roughness and elastic modulus of A- and Y-TSPC-loaded hydrogels. Lastly,

quantitative PCR revealed similar expression profiles, as well a significant upregulation of genes related to

tenogenesis and multipotency. Taken together, the RADA-based hydrogels exert a rejuvenating effect by recapitulating

in vitro specific features of the natural microenvironment of human TSPCs, which strongly indicates

their potential to direct cell behaviour and overcome the challenge of cell aging and degeneration in tendon

repair.