Effect of low intensity photobiomodulation associated with norbixin-based poly (hydroxybutyrate) membrane on post-tenotomy tendon repair. In vivo study

Abstract Purpose: To evaluate the in vivo response of photobiomodulation therapy associated with norbixin-based poly(hydroxybutyrate) membrane (PHB) in tenotomized calcaneal tendon. Methods: Thirty rats were randomly allocated to six groups (n=5 each): LED groups (L1, L2 and L3) and membrane + LED groups (ML1, ML2 and ML3). The right calcaneal tendons of all animals were sectioned transversely and were irradiated with LED daily, one hour after surgery every 24 hours, until the day of euthanasia. At the end of the experiments the tendons were removed for histological analysis. Results: The histological analysis showed a significant reduction in inflammatory cells in the ML1, ML2 and ML3 groups (p=0.0056, p=0.0018 and p<0.0001, respectively) compared to those in the LED group. There was greater proliferation of fibroblasts in the ML1 (p<0.0001) and L3 (p<0.0001) groups. A higher concentration of type I collagen was also observed in the ML1 group (p=0.0043) replacing type III collagen. Conclusion: Photobiomodulation in association with norbixin-based PHB membrane led to control of the inflammatory process. However, it did not favor fibroblast proliferation and did not optimize type I collagen formation in the expected stage of the repair process.

Effect of norbixin-based poly(hydroxybutyrate) membranes on the tendon repair process after tenotomy in rats

Abstract Purpose: To determine the efficacy of norbixin-based poly(hydroxybutyrate) (PHB) membranes for Achilles tendon repair. Methods: Thirty rats were submitted to total tenotomy surgery of the right Achilles tendon and divided into two groups (control and membrane; n = 15 each), which were further subdivided into three subgroups (days 7, 14, and 21; n = 5 each). Samples were analyzed histologically. Results: Histological analysis showed a significant reduction in inflammatory infiltrates on days 7, 14 (p < 0.0001 for both), and 21 (p = 0.0004) in the membrane group compared to that in the control group. There was also a significant decrease in the number of fibroblasts in the control group on days 7, 14 (p < 0.0001), and 21 (p = 0.0032). Further, an increase in type I collagen deposition was observed in the membrane group compared to that in the control group on days 7 (p = 0.0133) and 14 (p = 0.0107). Conclusion: Treatment with norbixin-based PHB membranes reduces the inflammatory response, increases fibroblast proliferation, and improves collagen production in the tendon repair region, especially between days 7 and 14.

Quantification of collagen fibers in canine uteri treated with medroxyprogesterone acetate

Collagen plays essential roles in remodeling uterine tissue during decidualization, implantation, pregnancy and involution. To understand whether the progestational agent medroxyprogesterone acetate (MPA) can modify the organization and deposit of collagen in the uteri of normal bitches (Canis Tlupus familiaris), we assessed uterine tissues by histochemistry. Uteri were grouped as: nulliparous (n=11), multiparous (n=11) and treated with MPA (n=11; nulliparous with two treatments; 5mg/kg; i.m.). The amount, location and birefringence of interstitial collagen types I and III in the fold and base of the endometrial stroma and the myometrial muscular layers were studied on sections stained with Picrosirius Red by polarized light microscopy and evaluated by ANOVA. No differences were observed in the endometrium. In the myometrium, differences were observed in collagen type I between MPA-treated and nulliparous uteri vs. multiparous (p<0.05), and differences in collagen type III between nulliparous and multiparous uteri vs. MPA-treated (p=0.0001). In conclusion, two doses of MPA had no significant effect on the investigated collagens in the extracellular matrix.(AU)

Effect of propranolol on capsular reaction around silicone implants in guinea pigs

PURPOSE: To evaluate the effect of propranolol on capsular architecture around silicone implants by measuring the inflammation, capsular thickness, and collagen fiber density, using a guinea pig experimental model. METHODS: Thirty six adult male guinea pigs randomly divided into two groups (n=18) were used. Each one received a silicone implant with textured-surface. The capsular tissue around implants from untreated or treated animals with the beta-adrenoceptor antagonist propranolol (10 mg/kg, dissolved in daily water) were analyzed for inflammation by histological scoring, capsular thickness by computerized histometry, and collagen fibers type I and Type III density by picrosirius polarization at different time points (7, 14 or 21 days after silicone implantation). RESULTS: Propranolol treatment reduced inflammation and impaired capsular thickness and delayed collagen maturation around the textured implant. CONCLUSION: Propranolol reduces the risk of developing capsular contracture around silicone implants with textured surface. .

Qualitative analysis of the deposit of collagen in bladder suture of rats treated with tacrolimus combined with mycophenolate-mofetil

PurposeTo evaluate the synthesis of type I (mature) and type III (immature) collagen in bladder suture of rats treated with a combination of tacrolimus and mycophenolate mofetil for 15 days.Materials and MethodsThirty rats were divided into 3 groups: the sham, control and experimental groups. All the animals underwent laparotomy, cystotomy and bladder suture in two planes with surgical PDS 5-0 thread. The sham group did not receive treatment. The control group received saline solution, and the experimental group received 0.1mg/kg/day of tacrolimus with 20mg/kg/day of mycophenolate mofetil, for 15 days. From then on, the tacrolimus was dosed. The surgical specimens of the bladder suture area were processed so that the total type I and type III collagen could be measured by the picrosirius red technique.ResultsThere was a predominance of type I collagen production in the sham and control groups compared to the experimental group, in which type III collagen was predominant. The production of total collagen did not change.ConclusionThe association of tacrolimus and mycophenolate mofetil in animals qualitatively changes the production of collagen after 15 days with a predominance of type III collagen.

Effect of angiotensin-converting enzyme inhibitors, captopril and lisinopril, on collagen synthesis by cultured rat liver cells

Several studies have documented the role of angiotensin-converting enzyme inhibitors [ACEI] as antifibrogenic and antiproliferative in different tissues in vivo and in vitro but unfortunately non of them has investigated this effect on collagen synthesis by individual liver cells. In this study we focused on the in vitro effect of two ACEI with different pharmacologic properties, captopril and lisinopril, on the synthesis of types I and III collagens by individual liver cells, since these types of collagens are the most abundant ECM molecules both in normal and fibrotic liver. Rat liver cells were isolated, separated according to cell types through density gradient centrifugation in percoll then cultured as separate clones for 24 hours. Types I and III collagens secretion was measured by gel electrophoresis [SDS-PAGE] and computer analysis of their alpha chains after purification from cell culture media. Both captopril and lisinopril significantly reduced types I and III collagens by cultured hepatocytes [HC], liver endothelial cells [EC], and hepatic stellate cells [HSC] with more prominent action for captopril than lisinopril. The present study document the inhibitory effect of ACEI on types I and III collagen synthesis by liver cell sub-population in vitro by a mechanism independent on the systemic angiotensin-converting enzyme inhibition and possibly through a mechanism involving a local renin-angiotensin system or interference with intracellular events involved in collagen synthesis