BACKGROUND:With good biocompatibility, bioactivity, control able biodegradation rate, amorphous calcium phosphate is considered as a natural reservoir of calcium and phosphorus, which has been widely used in the biomedical field. OBJECTIVE:To review the latest progress of amorphous calcium phosphate in biomedicine based on its clinical application and characteristics. METHODS:A computer-based search of CNKI, Wanfang database and PubMed database from January 1980 to June 2014 was performed for articles relevant to amorphous calcium phosphate materials with the key words of“amorphous calcium phosphate, biomaterials”in Chinese and English. RESULTS AND CONCLUSION:Amorphous calcium phosphate has been widely used in orthodontic care, bone substitutes, drug delivery material and stents, but it is stil in the developmental stage for the special low differentiated cells, cytokines, targeted drug delivery materials and new biodegradable coronary stent. Based on amorphous calcium phosphate, there are various possible treatments for human diseases. But we cannot blindly exaggerate its advantages but outweigh its disadvantages. For example, whether it wil increase the formation of dental calculus during prevention of dental caries? Whether it wil promote its adjacent tissue calcification or hardening? And whether there are risks leading to vascular calcification or hardening? The advantages and disadvantages of amorphous calcium phosphate when used in human are stil needed to carry out a large scale and long-time research.

BACKGROUND:In recent years, pathological calcification such as vascular calcification has been an active deposition of the mineralizer in the abnormal parts, can promote the occurrence and development of many diseases. Moreover, extensive studies believe that micro-inflammatory state is strongly associated with pathological calcification. OBJECTIVE:To further summarize the relationship between micro-inflammatory state and calcification based on the relationship between inflammatory factor and calcification-related factors. METHODS: A computer-based search of CNKI, Wanfang database and PubMed database from January 2000 to January 2015 was performed for articles addressing the relationship between micro-inflammatory state and calcification. The key words were “calcification, micro-inflammatory state, inflammatory factor” in Chinese and English. RESULTS AND CONCLUTION:Micro-inflammatory state is a non-dominant inflammatory state, caused by an infection of non-pathogenic microorganisms, mainly for the elevated inflammatory protein, inflammatory cytokines in the systemic circulation. At present, pro-inflammatory cytokines interleukin-1, interleukin-6, interleukin-8, tumor necrosis factor-alpha and acute phase protein C reactive protein were considered as the objective and sensitive detection index of micro-inflammation state. A large number of studies have found that a slight elevation of interleukin-1, interleukin-6, interleukin-8, tumor necrosis factor-alpha and C reactive protein was positively correlated with calcification promoting factors, which ilustrated that the micro-inflammatory state has the role of promoting the calcification.

BACKGROUND:Novel fuly biodegradable poly-L-lactic acid/amorphous calcium phosphate (PLLA/ACP) scaffold shows a good prospect of application, but whether the scaffold material has impact on the surrounding tissue calcification is unknown. OBJECTIVE: To observe the influence of PLLA/ACP scaffold material on the calcification of surrounding tissue after implantation of PLLA/ACP scaffold into rats. METHODS:A total of 48 SD rats were divided into experimental group and control group randomly. The experimental group was implanted with PLLA/ACP scaffold material, while the control group was implanted with PLLA scaffold material. At 1, 2, 4, 12 weeks after implantation, the liver function, kidney function and concentrations of calcium, phosphorus, alkaline phosphatase in serum were detected; the muscle tissue around the scaffold was colected for hematoxylin-eosin staining, Von Kossa staining, alkaline phosphatase staining and immunohistochemical staining of nuclear factor-kappa B. Then, western blot assay was used to detect the contents of interleukin-6, bone morphogenetic protein-2, and meanwhile, the contents of calcium and alkaline phosphatase in tissue homogenate were measured. RESULTS AND CONCLUSION:There was no significant difference in either group about the liver and kidney functions at each time. The content of interleukin-6 in the experimental group was less than that in the controlgroup at 2, 4 and 12 weeks after implantation (P < 0.05). The positive expression of nuclear factor-kappa B, bone morphogenetic protein-2 and inflammatory cel count in the experimental group were less than those in the control group at 4 and 12 weeks after implantation (P < 0.05). The content of calcium in the experimental group was less than that in the control group at 12 weeks after implantation (P < 0.05). No difference was found in the expression of alkaline phosphate, the Von Kossa staining and the content of calcium, phosphorus, alkaline phosphatase in the muscle tissue around the scaffold between the two groups (P > 0.05). These findings indicate that the PLLA/ACP scaffold has a good biocompatibility and biological security, which cannot induce peripheral tissue calcification.

BACKGROUND:In order to solve the problems of poly-l-lactic acid (PLLA) stents, such as poor support, acidic metabolites, we researched a novel biogradable stent-PLLA/amorphous calcium plosphate (ACP).
OBJECTIVE: To discuss the safety and histocompatibility of the novel biogradable stent-PLLA/ACP stent implanted in the coronary artery in a porcine model.
METHODS:Sixteen novel biogradable stents were randomly implanted into the coronary arteries, left anterior descending branch, left circumflex artery or right coronary artery of sixteen healthy Tibet miniature pigs. The blood routine and blood biochemistry were measured pre-operation and at 1 month after operation. The coronary blood vessels where the stent was implanted were examined by hematoxylin-eosin staining at 1 and 6 months after operation.
RESULTS AND CONCLUSION: Compared with pre-operation, the post-operation indicators of the blood routine and blood biochemistry were of no significant difference. Coronary angiography revealed coronary artery patency and no thrombosis, the vascular stent segments exhibited clear boundaries with the surrounding tissue, with no tissue adhesion, necrosis, and adherence abnormalities. The results of hematoxylin-eosin staining showed that there was no significant difference in vascular injury integral between 1 month after operation and 6 months after operation. However, 6 months after operation, the scores of the inflammation were lower (P < 0.05), and the scores of the endothelialization were increased (P < 0.05). There was no myocardial infarction and inflammatory cellinfiltration around the stent. These results suggest that the novel biodegradable stent has good safety and histocompatibility.