OBJECTIVE: To review the development and mechanism of platelet-rich plasma (PRP) and the unsolved problems so as to provide reference for the clinical application of PRP.DATA SOURCES: Articles on effects of platelet-rich plasma on bone repair are searched from Medline between January 1995 and June 2005 on computer. The key words were platelet rich plasma, bone, and repair.Meanwhile, the same search was conducted to determine the correlated articles during January 1998 to June 2005 from Wanfang database with key words of platelet-rich plasma, bone and repair in Chinese.STUDY SELECTION: Literatures at home and abroad on the PRP and bone repair were chosen; Non-randomized controlled literatures were included.DATA EXTRACTION: Totally 40 out of 49 reports related to PRP and bone repair met the criteria. 9 reports were excluded due to the repeated same research. The rest 40 reports were sorted out and conducted literature review.DATA SYNTHESIS: Platelet-rich plasma was originally used in clinic to repair mandibular defect in 1998, by adding PRP to grafts with a radiographic maturation rate 1.62 to 2.16 times that of grafts without PRP. Up to now, PRP has been used in many medical areas to accelerate tissue healing due to its advantages of safety, simple, low-cost. But some problems still remain to be studied and solved.CONCLUSION: PRP includes many sorts of growth factors and has been proved to be beneficial to the maturation of both bone tissue and soft tissues. PRP is autologous and can be produced easily and safely from autologous blood, without the concerns of transmissions and immunological rejection of various diseases.

Objective: To summarize the bioactive substances contained in bacterial extracellular vesicles (EVs) and their mechanisms in mediating bacterial-bacterial and bacterial-host interactions, as well as their mechanisms for use in implant infection-associated clinical guidance. Methods: A wide range of publications on bacterial-derived EVs were extensively reviewed, analyzed, and summarized. Results: Both gram-negative bacteria (G - bacteria) and gram-positive bacteria (G + bacteria) can secrete EVs which contain a variety of bioactive substances, including proteins, lipids, nucleic acids, and virulence factors, and mediate bacterial-bacterial and bacterial-host interactions. EVs play an important role in the pathogenic mechanism of bacteria. Conclusion: Bioactive substances contained within bacteria-derived EVs play an important role in the pathogenesis of bacterial infectious diseases. In-depth study and understanding of their pathogenic mechanisms can provide new insights which will improve early clinical diagnosis, prevention, and treatment of implant-associated infection. However, at present, research in this area is still in its infancy, and many more in-depth mechanisms need to be further studied.

In order to investigate the effect of degradable products on degradable property of PGLA in vitro, two kinds of media-PBS and artificial plasma were prepared for immersing PGLA under changing or non-changing media condition. The mass loss rate of PLGA was calculated and the pH value in the non-changing media was measured before and after immersing 2 w, 3 w, 4 w, 6 w, 8 w and 10 w respectively. The results showed that there was almost no statistically significant difference of mass loss rate of PGLA immersing in two kinds of media at 2 w (P > 0.05). But from 2 w to 6 w, the degradation of PGLA immersing in both media under non-changing media group was remarkably faster than those at the same period of changing media group (P < 0.01). During the whole degradable period, the pH value in PBS kept stable around 7.0-7.4, while the pH value in artificial plasma showed gradually decreased as the degradation of PGLA from 7.5 to 5.7. The change of pH values had statistically significant difference between two degradable media (P < 0.01). It was implied that the degradable products existed in immersing media had an effect on degradable speed of PGLA itself if the media was unchanged. It could accelerate the mass loss of material. The pH value also affected the degradable property of PGLA, the lower the pH value, the slower the degradable speed.
Antimicrobial Cationic Peptides ; metabolism ; Biocompatible Materials ; metabolism ; Biodegradation, Environmental ; Blood Substitutes ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Materials Testing

The biological safety of degradable products is a key point in biological evaluation of biodegradable materials. This paper deals with an investigation of the influence of PGLA degradable products on physiologic function of liver and kidney by detecting the "before-after change" of some biochemical indexes with the use of self-control method. PGLA materials of different sizes were implanted into the subcutaneous tissue of Wistar rats and New Zealand rabbits respectively. Also for the purpose of group comparison, only surgical operation was performed on other animal at the same site (control group). The concentrations of urea nitrogen, uric creatinine, blood urea nitrogen (BUN), carbamide (Cr) and serum glutamio pyruvic transaminase (GPT) were measured before and after implantation (from 2 w to 10 w). The results showed the values of urea nitrogen and uric creatinine were significantly increased at 2-3 weeks after implantation (P < 0.01). After 2 weeks of implantation, the concentration of GPT was slightly decreased (P < 0.05). The BUN and Cr were remarkably increased (P < 0.01). But at the 4th week, all the values returned to normal and kept stable thenceforth. All the biochemical indexes in the control animal exhibited no abnormal change after operation. These results indicated: (1) There are no permanent harmful effects of PGLA degradable products on the function of liver and kidney; (2) By means of self-control and measurements of some biochemical indexes in the blood or urea, the method is suitable for evaluating the biological safety of degradable products; (3) The method has the advantages for evaluating the bioaccept ability of degradable products during the life period, it is objective and sensitive, the number of animal can be decreased, the process of dynamic change in vivo can be observed directly, and the effect of degradable products on physical function can be evaluated. Therefore, the method can provide a new approach for biological evaluation of biodegradable materials.
Absorbable Implants ; adverse effects ; Animals ; Biodegradation, Environmental ; Female ; Glycolates ; adverse effects ; chemistry ; Implants, Experimental ; Kidney ; physiology ; Lactic Acid ; Liver ; physiology ; Male ; Materials Testing ; Polyglycolic Acid ; Rabbits ; Rats ; Rats, Wistar