Injectable hydrogel loaded with bone marrow-mesenchymal stem cells promotes the repair of cartilage defect
Objective To construct an injectable hydrogel(IH)entrapment system of bone marrow mesenchymal stem cells(BM-MSCs)and to explore its effect of promoting articular cartilage repair and underlying mechanism.Methods The primary BM-MSCs of mice were cultured by whole bone marrow adherent method.The differentiation potential was identified by alizarin red(ARS),oil red O(ORO)and Alcian blue(AB)staining,and the expres-sion of CD44,CD90,CD105,CD34 and CD45 on the surface was detected by flow cytometry.BM-MSCs loaded with IH(BM-MSC-IH)was prepared,and the rheological properties of BM-MSC-IH were tested by rheological test.The model of full-thickness injury of knee cartilage in mice was established,and the mice were randomly divided into normal saline group,BM-MSC group and BM-MSC-IH group with 8 in each.The mice were injected with BM-MSC-IH 0.2 mL,cell suspension 0.2 mL and 0.9%NaCl solidion,independently.After 6 and 12 weeks of in-jection,the repair of knee cartilage in mice was observed by safranin-fast green staining,and the expression of typeⅡ collagen in knee joint was examined by immunohistochemical staining microscopy.Results The primary cultured cells showed positive expression of CD44,CD90 and CD105,but negative expression of CD34 and CD45,and had the potential of osteogenic,adipogenic and chondrogenic differentiation.The constructed BM-MSC-IH sys-tem was solid colloid,and the rheological properties were consistent with the basic characteristics of hydrogel.BM-MSC-IH effectively promoted the regeneration of mouse knee cartilage and increase the local expression of typeⅡ collagen.Conclusions Bone marrow-mesenchymal stem cells embedded with injectable hydrogel effectively pro-mote the repair of injured cartilage and the underlying mechanism is potentially promoting the differentiation of chondrocytes and the expression of type Ⅱ collagen.Its effect is better than application of BM-MSCs alone.