RESUMO
The collagenous matrix plays a fundamental role in the process of bone regeneration, so it is essential to study how it is primarily formed in situations in which critical bone defects are created. Objective: this study seeks to quantify the collagenous matrix formed in critical bone defects in the calvaria of mice over the process of bone regeneration promoted by the association of poly(lactide-co-glycolide) (PLGA) porous scaffolds and stem cells from deciduous teeth (SCDT). In addition, this study attempted to establish a precise protocol for the digital quantification of collagen through a histological method. Materials and method: Nine Wistar rats were used, in which critical defects of 8.0 mm of diameter were made in their calvarium. The animals were divided into three groups (n = 9): I PLGA scaffolds; II PLGA scaffolds/SCDT; III PLGA scaffolds/SCDT maintained in osteogenic medium for 13 days. Within sixty postoperative days, calvaria were removed for histometric analysis following a digital protocol. A specific digital analysis method was designed for this study, in which a more precise quantification and differentiation between collagen fibers and non-collagenous tissue was possible, excluding factors that would normally alter the results. Results: it was noted that the association of PLGA scaffolds and SCDT maintained in osteogenic medium resulted in collagen matrix formation statistically higher than the other groups (p<0.05). Conclusion: the protocol designed for collagen quantification was precise and efficient, producing methodologically standardized results.
RESUMO
AIM: To evaluate the effect of LLLT (780 nm; 10 J/cm2 , 40 mW, 3.2 J) prior to injury on the morphological analysis, collagen deposition, and activity of matrix metalloproteinase-2 (MMP-2). METHODS: Wistar rats were divided into groups: control; sham; only LLLT; only muscle injury and LLLT + injury. The rats were euthanized at 1, 3, and 7 days following cryoinjury to muscle that was removed for analysis. RESULTS: LLLT applied prior to muscle injury led to a reduction in myonecrosis and inflammatory cells, an increase of blood vessels and immature muscle fibers. An increase in MMP-2 activity and a decrease in collagen deposition were also found, with a better collagen organization and distribution. CONCLUSION: LLLT applied immediately prior to injury had positive effects during the muscle regeneration process. Therefore, this resource may have considerable therapeutic value, especially for athletes who practice sports in which there is a constant risk of muscle injury. Lasers Surg. Med. 47:571-578, 2015. © 2015 Wiley Periodicals, Inc.