Experimental Evaluation of Chitosan Membrane and Collagen Sponge (TachoSil®) as Sealants in Cardiovascular Surgery.

INTRODUCTION: The objectives of this study are to experimentally evaluate the haemostatic effects of two organic substances, a membrane of chitosan and a collagen sponge coated with thrombin and human fibrinogen (TachoSil®), in sealing 7-0 needle stitches holes on the femoral arteries of rats as well as to evaluate local histological reactions. METHODS: Twenty-four rats were included, and four holes were made in each common femoral artery. In the control group, haemostasis was achieved only by compression with gauze sponge; and in the two other groups, haemostasis was achieved with application of one of these two substances. RESULTS: Membrane of chitosan and TachoSil® showed a power to reduce the time to achieve haemostasis compared with the control group (P=0.001), and the haemostatic effects of these two substances were comparable. There was lower blood loss in the groups where these two substances were used when compared with the control group, but no difference was found comparing the two substances. CONCLUSION: The use of these sealants did not promote more adhesion or local histological reactions when compared to the control group. Since chitosan is easy to find in nature, has a positive effect to promote haemostasis, and did not bring considerable local reactions, it might be used as a sealant in cardiovascular surgery.

Experimental Evaluation of Chitosan Membrane and Collagen Sponge (TachoSil®) as Sealants in Cardiovascular Surgery

ABSTRACT Introduction: The objectives of this study are to experimentally evaluate the haemostatic effects of two organic substances, a membrane of chitosan and a collagen sponge coated with thrombin and human fibrinogen (TachoSil®), in sealing 7-0 needle stitches holes on the femoral arteries of rats as well as to evaluate local histological reactions. Methods: Twenty-four rats were included, and four holes were made in each common femoral artery. In the control group, haemostasis was achieved only by compression with gauze sponge; and in the two other groups, haemostasis was achieved with application of one of these two substances. Results: Membrane of chitosan and TachoSil® showed a power to reduce the time to achieve haemostasis compared with the control group (P=0.001), and the haemostatic effects of these two substances were comparable. There was lower blood loss in the groups where these two substances were used when compared with the control group, but no difference was found comparing the two substances. Conclusion: The use of these sealants did not promote more adhesion or local histological reactions when compared to the control group. Since chitosan is easy to find in nature, has a positive effect to promote haemostasis, and did not bring considerable local reactions, it might be used as a sealant in cardiovascular surgery.

Osseointegration Improvement of Co-Cr-Mo Alloy Produced by Additive Manufacturing.

Cobalt-base alloys (Co-Cr-Mo) are widely employed in dentistry and orthopedic implants due to their biocompatibility, high mechanical strength and wear resistance. The osseointegration of implants can be improved by surface modification techniques. However, complex geometries obtained by additive manufacturing (AM) limits the efficiency of mechanical-based surface modification techniques. Therefore, plasma immersion ion implantation (PIII) is the best alternative, creating nanotopography even in complex structures. In the present study, we report the osseointegration results in three conditions of the additively manufactured Co-Cr-Mo alloy: (i) as-built, (ii) after PIII, and (iii) coated with titanium (Ti) followed by PIII. The metallic samples were designed with a solid half and a porous half to observe the bone ingrowth in different surfaces. Our results revealed that all conditions presented cortical bone formation. The titanium-coated sample exhibited the best biomechanical results, which was attributed to the higher bone ingrowth percentage with almost all medullary canals filled with neoformed bone and the pores of the implant filled and surrounded by bone ingrowth. It was concluded that the metal alloys produced for AM are biocompatible and stimulate bone neoformation, especially when the Co-28Cr-6Mo alloy with a Ti-coated surface, nanostructured and anodized by PIII is used, whose technology has been shown to increase the osseointegration capacity of this implant.

Effects of the combination of low-level laser therapy and anionic polymer membranes on bone repair.

In view of the limitations of bone reconstruction surgeries using autologous grafts as a gold standard, tissue engineering is emerging as an alternative, which permits the fabrication and improvement of scaffolds to stimulate osteogenesis and angiogenesis, processes that are essential for bone repair. Polymers are used to mimic the extracellular bone matrix and support cell growth. In addition, bone neoformation can be induced by external factors such as laser irradiation, which stimulates bone metabolism. The objective of this study was to evaluate the regeneration of bone defects using collagen and elastin membranes derived from intestinal serosa and bovine auricular cartilage combined with low-level laser application. Thirty-six Wistar rats were operated to create a 3-mm defect in the distal metaphysis of the left femur and divided into six groups: G1 (control, no treatment); G2 (laser); G3 (elastin graft), G4 (elastin+laser); G5 (collagen graft); G6 (collagen+laser). The animals were sacrificed 6 weeks after surgery and the femurs were removed for analysis of bone repair. Macroscopic and radiological results showed the absence of an infectious process in the surgical area. This was confirmed by histological analysis, which revealed no inflammatory infiltrate. Histomorphometry showed that the formation of new bone started from the margins of the bone defect and its volume was greater in elastin+laser and collagen+laser. We conclude that newly formed bone in the graft area was higher in the groups that received the biomaterials and laser. The collagen and elastin matrices showed biocompatibility.

Viability Assays of PLLA Fibrous Membranes Produced by Rotary Jet Spinning for Application in Tissue Engineering

Abstract Tissue engineering suggests different forms to reconstruct tissues and organs. One of the ways is through the use of polymeric biomaterials such as poly(L-lactic acid) (PLLA). PLLA is a recognized material in tissue engineering due to its characteristics as biocompatibility and bioresorbability. In this work PLLA fibrous membranes were produced by a simple technique known as rotary jet spinning. The rotary jet spinning consists of fibrous membranes production, with fibers of scale nano/micrometric, from a polymeric solution through the centrifugal force generated by the equipment. The membranes formed were subjected to preliminary in vitro assays to verify the cytotoxicity of the membranes made in contact with the cells. Direct cytotoxicity assays were performed through the MTT, AlamarBlue® and Live/Dead® tests, with fibroblastic and osteoblastic cells. The results obtained in this study showed that PLLA membranes produced by rotary jet spinning showed promising results in the 24-hours contact period of the cells with the PLLA fibrous membranes. The information presented in this preliminary study provides criteria to be taken in the future procedures that will be performed with the biomaterial produced, aiming at its improvement.

Short-term PTH administration increases dentine apposition and microhardness in mice.

OBJECTIVE: The purpose of this study is to investigate the effects of intermittent parathyroid hormone (PTH) administration on the apposition rate and structural features of dentine from mouse incisors. METHODS: Young male A/J Unib mice were treated daily for 6 and 10 days with 40 µg/kg of hPTH 1-34 or a vehicle. Dentine apposition rates measured by fluorescent labels (tetracycline and calcein) and alkaline phosphatase (ALP) plasma levels were evaluated after 6 days of treatment. Knoop microhardness testing and element content measurements in at.% of calcium (Ca), phosphorus (P), oxygen (O), and magnesium (Mg) in the peritubular and intertubular dentine were performed by Energy Dispersive X-ray (EDX) microanalysis via Scanning Electron Microscopy (SEM) after 10 days of treatment. RESULTS: Histometric analysis revealed an increase of 5% in the apposition rate of dentine and 25% in the ALP plasma levels in the PTH treated group. In addition, knoop microhardness testing revealed that the animals treated with PTH had a greater microhardness (11%). EDX microanalysis showed that PTH treatment led to increases in P (23%) and Ca (53%) at.% content, as well as the Ca/P ratio (24%) in peritubular dentine. The chemical composition of intertubular dentine did not vary between the groups. CONCLUSIONS: These findings indicate that intermittent administration of hPTH (1-34) increases apposition and mineralization of the dentine during young mice incisor formation.

O papel das células tronco na engenharia tecidual / The use of stem cells in tissue engineering

A engenharia tecidual é um campo de estudo que abrange diversas áreas do conhecimento, e em maior intensidade as áreas médica, biológica e da engenharia. A utilização de células tronco na bioengenharia tem sido muito investigada e está se revelando como uma linha promissora também em engenharia tecidual, embora apresente algumas controversas e discussões. Esse trabalho é uma revisão a respeito das características das células tronco, assim como suas classificações, focalizando em sua potencialidade na engenharia tecidual(AU)

Tissue engineering is an interdisciplinary field that involves mainly medical area, biology and engineering. The uses of stem cells in bioengineering have been much investigated and it is showing a promising research line also in tissue engineering, although there are some controversies and discussions. This work is a review regarding the characteristics of stem cells focusing in their potentiality in tissue engineering(AU)