Multifunctional inverse opal microcarriers-based cytokines delivery system with stem cell homing capability for osteoarthritis treatment

Osteoarthritis has been regarded as a complex and serious degenerative disease.Attempts in this area are focused on improving the curative effect of stem cell-based therapies.In this work,we present a novel inverse opal microcarriers-based cytokines delivery system to induce autologous stem cell homing for osteoarthritis treatment.Considering their important role in stem cell recruitment and chondro-genic differentiation respectively,platelet-derived growth factor BB(PDGF-BB)and transforming growth factorβ3(TGF-β3)are loaded into inverse opal microcarriers as model cytokines.Since cytokine release induces the corresponding variations in characteristic reflection spectra and structural colors,the inverse opal microcarriers possess the optical self-reporting capacity to monitor the release process.In vitro cell experiments reveal that inverse opal microcarriers could successfully recruit the gathering of mesenchymal stem cells through the release of loaded cytokines.Based on these features,we have demonstrated the enhanced therapeutic effect of PDGF-BB and TGF-β3 loaded inverse opal microcarriers in the treatment of rat osteoarthritis models.These results indicate that the multifunctional inverse opal microcarriers-based cytokines delivery system wouldfind broad prospects in osteoarthritis treatment and other biomedicalfields.

Stem cell homing-based tissue engineering using bioactive materials

Tissue engineering focuses on repairing tissue and restoring tissue functions by employing three elements： scaffolds, cells and biochemical signals. In tissue engineering, bioactive material scaffolds have been used to cure tissue and organ defects with stem cell-based therapies being one of the best documented approaches. In the review, different biomaterials which are used in several methods to fabricate tissue engineering scaffolds were explained and show good properties （biocompatibility, biodegradability, and mechanical properties etc.） for cell migration and infiltration. Stem cell homing is a recruitment process for inducing the migration of the systemically transplanted cells, or host cells, to defect sites. The mechanisms and modes of stem cell homing-based tissue engineering can be divided into two types depending on the source of the stem cells： endogenous and exogenous. Exogenous stem cell-based bioactive scaffolds have the challenge of long-term culturing in vitro and for endogenous stem cells the biochemical signal homing recruitment mechanism is not clear yet. Although the stem cell homing-based bioactive scaffolds are attractive candidates for tissue defect therapies, based on in vitro studies and animal tests, there is still a long way before clinical application.