Chondrogenic stimulation in mesenchymal stem cells using scaffold-based sustained release of platelet-rich plasma

Developing minimal invasive strategies via injectable hydrogels for effective repairing of cartilage defects is highly desired. Injectable hydrogels, which can simultaneously embed cell and growth factors (GFs), serve as in situ formed scaffolds and could support an accelerated tissue regeneration process. The purpose of this study is to fabricate a composite injectable hydrogel, based on alginate (Alg)/polyvinyl alcohol (PVA) incorporating platelet rich plasma (PRP)-encapsulated Alg sulfate (AlgS) microbeads, as a localized sustained release system of GFs, for the articular cartilage regeneration. The results show that synthesized AlgS microbeads support the sustained release of PRP GFs during 14 days, where preserve the bioactivity of them more than the free PRP. Rabbit adipose-derived mesenchymal stem cells in contact with PRP-loaded AlgS beads show more proliferation (2.7 folds) and have obviously higher deposition of collagen type ΙΙ and GAGs than free PRP treated ones. In addition, cells encapsulated into the hydrogel including PRP sustained release system show upregulated expression of collagen type ΙΙ (61 folds), Aggrecan (294 folds) and SOX9 (71.5 folds), as cartilage-critical genes, compared to the direct treatment by PRP. To summarize, the developed hybrid Alg/PVA hydrogel embedding with PRP-encapsulated AlgS microbeads is suggested as a potential in situ formed scaffold for cartilage regeneration.