Injectable PHEMA/CPC Composite Hydrogel Films:Preparation And Biocompatibility In Vitro

Objective:To provide an alternative to traditional strategies to repair the mandibular condylar cartilage defects with minimally invasive surgery, novel injectable polyhydroxyethyl methacrylate (PHEMA) and calcium phosphate bone cement (CPC) composite hydrogels films were synthesized using microwave-assisted polymerization technique and characterized.Methods:(1) In this study,2-hydroxyethyl methacrylate (HEMA) as raw material, potassium persulfate and polycaprolactone (PCLI) as initiator, polycaprolactone (PCLX) as crosslinker polymerized under microwave. Then, the PHEMA/CPC composites were obtained by physically crosslinking with calcium phosphate cement (CPC). Tests using infrared spectroscopy (IR), NMR spectroscopy and scanning electron microscopy (SEM) were conducted to provide experimental evidence for a series of subsequent biological behavioral experiments.(2) Tests of physical and chemical properties such as swelling ratio, gelation time, mechanical properties, injectability and in vitro degradation were conducted to select the best physical and chemical properties.(3) Using MTT method and flow cytometry, the best PHEMA/CPC composites were tested on L929cell proliferation, cycle and apoptosis. And real-time PCR was used to monitor the expression of cell apoptosis related genes. Hemolysis test was also used to further evaluate the biocompatibility of PHEMA/CPC composites.Results:The experimental results from IR, NMR and SEM tests showed that PHEMA/CPC composites were synthesized successfully. The experimental results from physical and chemical tests showed the best physical and chemical properties were PHEMA/CPC in the ratio98:2. The third part of the experimental results showed that the MTT method detected relative growth rates of L929cells on24th hour,48th hour and72th hour were all above85%. The toxicity level was1, indicating the PHEMA/CPC group did not have significant cytotoxicity. The hemolysis of PHEMA/CPC group was1.99%which was smaller than5%and qualified for the hemolysis test. Flow cytometric tests showed that the cell cycle of the PHEMA/CPC group did not show significant statistical difference from the control group (P>0.05). Quantitative tests of cell apoptosis types by Annexin V-FITC/PI double staining apoptosis kit indicated no significant statistical difference between PHEMA/CPC group and the control group (P>0.05). Real-time PCR showed the expressions of both Bcl-2and Bax mRNA in the PHEMA/CPC group showed no significant statistical difference from the control group (P>0.05).Conclusions:The novel injectable PHEMA/CPC composite (98:2) has stronger mechanical properties compared to PHEMA and other materials. It is biodegradable and biocompatible, thereby being a good candidate for repair of mandibular condylar cartilage defects.