聚己内酯包载过氧化钙微粒的制备、表征及其生物相容性研究

OBJECTIVE: To explore the physicochemical characteristics and biocompatibility of calcium peroxide (CPO)-loaded polycaprolactone (PCL) microparticle. METHODS: The CPO/PCL particles were prepared. The morphology and elemental distribution of CPO, PCL and CPO/PCL particles were observed with scanning electron microscopy and energy dispersive spectroscopy, respectively. Rat adipose mesenchymal stem cells were isolated and treated with different concentrations (0.10%, 0.25%, 0.50%, 1.00%) of CPO or CPO/PCL particles. The mesenchymal stem cells were cultured in normal media or osteogenic differentiation media under the hypoxia/normoxia conditions, and the amount of released O(2) and H(2)O(2) after CPO/PCL treatment were detected. The gene expressions of alkaline phosphatase (ALP), Runt-associated transcription factor 2 (RUNX2), osteopontin (OPN) and osteocalcin (OCN) were detected by realtime RT-PCR. SD rats were subcutaneously injected with 1.00% CPO/PCL particles and the pathological changes and infiltration of immune cells were observed with HE staining and immunohistochemistry at day 7 and day 14 after injection. RESULTS: Scanning electron microscope showed that CPO particles had a polygonal structure, PCL particles were in a small spherical plastic particle state, and CPO/PCL particles had a block-like crystal structure. Energy dispersive spectroscopy revealed that PCL particles showed no calcium mapping, while CPO/PCL particles showed obvious and uniform calcium mapping. The concentrations of O(2)and H(2)O(2) released by CPO/PCL particles were lower than those of CPO group, and the oxygen release time was longer. The expressions of Alp, Runx2, Ocn and Opn increased with the higher content of CPO/PCL particles under hypoxia in osteogenic differentiation culture and normal culture, and the induction was more obvious under osteogenic differentiation conditions (all P<0.05). HE staining results showed that the muscle tissue fibers around the injection site were scattered and disorderly distributed, with varying sizes and thicknesses at day 7 after particle injection. Significant vascular congestion, widened gaps, mild interstitial congestion, local edema, inflammatory cell infiltration, and large area vacuolization were observed in some tissues of rats. At day 14 after microparticle injection, the muscle tissue around the injection site and the tissue fibers at the microparticle implantation site were arranged neatly, and the gap size was not thickened, the vascular congestion, local inflammatory cell infiltration, and vacuolization were significantly improved compared with those at day 7. The immunohistochemical staining results showed that the expressions of CD3 and CD68 positive cells significantly increased in the surrounding muscle tissue, and were densely distributed in a large area at day 7 after particle injection. At day 14 of microparticle injection, the numbers of CD3 and CD68 positive cells in peripheral muscle tissue and tissue at the site of particle implantation were lower than those at day 7 (all P<0.01). CONCLUSION: CPO/PCL particles have good oxygen release activity, low damage to tissue, and excellent biocompatibility.