RESUMO
BACKGROUND: Gentamicin bead chain is an effective drug delivery system for treatment of osteomyelitis, but it cannot be degraded, need to be removed by second operation, and can breed pathogens. As a result, biodegradable drug delivery systems become a hotspot. Nano-hydroxyapatite/poly(β-hydroxybutyrate-co-β-hydroxyvalerate)-polyethylene glycol-gentamicin (nano-HA/PHBV-PEG-GM-DDS) is considered to be a good choice for the current predicament. OBJECTIVE: To evaluate the acute or chronic toxic reactions of the whole body and local tissues, intracutaneous stimulation, cytotoxicity and hemolytic reactions after bone remodeling and implantation of nano-HA/PHBV-PEG-GM-DDS, thus providing a new kind of material for treating osteomyelitis. METHODS: Plastic nano-HA/PHBV-PEG-GM-DDS was prepared using plastic fibrin glue as microsphere scaffold and nano-HA as the core carrier of GM that was coated with PHBV and PEG. The acute, subacute/chronic toxicity, implantation, hemolysis, cytotoxicity and intracutaneous stimulation tests were performed according to the evaluated criteria of medical implanted materials as wel as biological and animal trials recommended in GB/T16886.1-1997. RESULTS AND CONCLUSION: The plastic nano-HA/PHBV-PEG-GM-DDS was nontoxic and caused no apparent changes in liver and kidney function and serum biochemical indexes. Pathological examination showed that the implanted material was covered with tissues, and inflammation changes accorded with the general regularity of inflammatory outcomes. After implantation, the nano-HA/PHBV-PEG-GM-DDS was biodegraded and replaced by osseous tissues. The hemolytic rate of the material extract to the composite diffusion solution was 1.2%, which was below the standard criteria (5%). Human bone marrow cells cultured in vitro with the plastic nano-HA/PHBV-PEG-GM-DDS grew normally with good morphology. There was no stimulation reaction according to the criteria after the diffusion solution was subcutaneously injected into the back of the animal. These findings indicate that the plastic nano-HA/PHBV-PEG-GM-DDS for treating osteomyelitis possesses excel ent biocompatibility and security.
RESUMO
[Objective] To recommend an ideal method for extracting Ⅰ-collagen from cortical bone.[Method]The cortical bone of pig was splitted into small pieces after the soft tissues were cleaned up.The bone pieces were gradually dehydrated in alcohol,defatted in aether,decalcificated in hydrochloric acid,redefatted in chloroform:methanol(1:1,v/v)and became soft.The soft pieces were disintegrated into demineralized bone matrix(DBM)powder in a high speed mill.The osseins were extracted respectively by enhanced pepsin digestion method or alkali-solution method after the DBM powder was treated with desolving,centrifuging,dialyzing and lyophilization.The product got by enhanced pepsin digestion method was further confirmed.The extraction rate and appearance,viscosity and solidification of both products were analyzed and compared.[Result]The collagen produced by extraction of enhanced pepsin digestion method was confirmed to be I-collagen by analyzing amino-acid composition,protein electrophoresis,relative moleculas weight and max wavelength about light absorption.The extraction rate of Ⅰ-collagen by enhanced pepsin digestion method was(94.0?14.96)% as comparision with by alkali-solution method(57.8?4.96)% and the viscosity test of acetic and solution at the concentration 0.03%(w/v)was 3.71 and 2.81 respectively.At the condition of 37?,pH 7.35~7.45,the collagen solution extracted by enhanced pepsin digestion method solidified and changed into a glue 10 minutes later,while the product solution by extraction with alkali-solution was still like a sticky liquid.[Conclusion]Ossein extracted from cortical bone with enhanced pepsin digestion method is a realⅠ-collagen.Compared with alkeli-solution extraction method,the enhanced pepsin digestion extraction method has advantages of higher extraction rate,better purity,better viscosity and fine solidification of the product,and is a choice to prepare the Ⅰ-collagen from cortical bone.