POSS-based Hydrogel Scaffold For The Study Of Articular Cartilage Injury Repair

In this paper,an organic-inorganic hybrid hydrogel scaffold system with a threedimensional structure similar to cartilage,suitable pore size,high water content and excellent biocompatibility was designed to face challenges such as joint cartilage damage repair.In order to improve the mechanical properties,appropriate degradation rate and good tissue adhesion of hydrogel scaffolds,an organic-inorganic hybrid hydrogel(POSS-PEEP/HA)based on POSS-poly(ethylethylene phosphate)(POSS-PEEP)and thiolated hyaluronic acid(HA-SH)was prepared to mimic the cartilage tissue microenvironment and sustainedly release transforming growth factorβ3(TGF-β3).In vitro experiments,the proliferation and cartilage differentiation of human mesenchymal stem cells(hMSCs)were detected.Furthermore,the repair effect of knee cartilage injury by POSS-PEEP/HA hydrogel was evaluated in vivo experiments.The study in this paper is divided into the following three parts:1.Synthesis and characterization of POSS-PEEP/HA hydrogels.The acrylated 8arm star-shaped POSS-poly(ethyl ethylene phosphate)(POSS-8PEEP-AC)and biocompatible HA-SH were synthesized.Mechanically enhanced and injectable POSSPEEP/HA hydrogels were formed by the michael addition reaction between POSS8PEEP-AC and HA-SH.The swelling ratio,porosity,mechanical properties,degradation rate and tissue adhesion were detected.The experimental results showed that POSS-PEEP/HA hydrogel had suitable pore size,good and stable mechanical properties,suitable degradation rate and cartilage tissue adhesion.2.The biocompatibility of POSS-PEEP/HA and the differentiation of hMSCs loaded in hydrogels in vitro.On the basis of preparing and studying the physicochemical properties of POSS-PEEP/HA hydrogel,hMSCs were loaded in hydrogels.Good biocompatibility was demonstrated by live/dead staining and CCK-8 assay for hMSC loaded in POSS-PEEP/HA hydrogels with or without TGF-β3.In the process of inducing chondrogenic differentiation of hMSCs loaded in hydrogels,the release rate of TGF-β3 reached 86.1±1.6%after day 15,which proves that the scaffold has a slow-release effect.POSS-PEEP/HA hydrogel enhanced the expression of cartilage-specific genes and proteins,and increased the content of cartilage-specific matrix.In addition,TGF-β3 further promoted the differentiation of hMSCs into chondrocytes by activating the SMAD signaling pathway.3.Evaluation of cartilage damage repair ability of POSS-PEEP/HA hydrogels in vivo.The effect of cartilage damage repair in vivo was evaluated by macroscopic and histological scoring,hematoxylin-eosin staining,saffin-solid green staining,and immunohistochemical staining of neotissues.The results showed that hydrogels loaded with hMSCs and TGF-β3 could promote the deposition of cartilage-specific matrices and the formation of hyaline cartilage.Finally,in this study,the components or degradants of the hydrogel were directly inj ected into the rat tail vein,and the favorable biosafety of the hydrogel system in vivo was demonstrated by recording the weight and hematoxylin-eosin staining of the major organs.In summary,a multifunctional hydrogel scaffold with excellent mechanical properties,suitable degradation rate,certain tissue adhesion and sustainedly release of growth factors was developed,which proved its excellent biocompatibility in vitro and vivo experiments,and further used it for chondrogenic differentiation of hMSCs and repair of cartilage damage.