Estudo da resistência cicatricial cutânea de ratos tratados com óleo de pequi (Caryocar brasiliense) / Study of skin scarring resistance of rats treated with pequi oil (Caryocar brasiliense)

Introdução: Existem vários estudos sobre a utilização do pequi (Caryocar brasiliense) no processo cicatricial; contudo, em poucos trabalhos desenvolvidos, avaliou-se resistência dos tecidos à tensão pós-tratamento. Objetivo: Analisar a tensão cicatricial em incisões cutâneas de ratos, após terapia com Caryocar brasiliense. Método: Vinte ratos Wistar, divididos em dois grupos (placebo/tratado), sofreram incisão cutânea no dorso. O grupo tratado recebeu doses diárias de óleo de Caryocar brasiliense, e o placebo aplicação de óleo mineral. Após sacrifício, em sete e quatorze dias pós-cirurgia, amostras de pele foram submetidas à análise tênsil-histológica. Resultados: Observou-se diferença significante intergrupos na força máxima de tração, assim como uma elevação da síntese de colágeno na área das lesões no grupo tratado com óleo Caryocar brasiliense. Conclusão: A terapia com óleo de Caryocar brasiliense aumenta a resistência tênsil da pele, melhorando a resposta reparacional, reduzindo riscos de deiscência e complicações pós-cirúrgicas.

Introduction: There are several studies on the use of Caryocar brasiliense in the scarring process; however, few studies have evaluated posttreatment skin tissue resistance to tension. Objective: To analyze the scar tension in skin incisions of rats after therapy Caryocar brasiliense. Method: Twenty Wistar rats were divided into two groups (placebo / rough) and suffered skin incision in dorso. The treatment group received daily dose of Caryocar brasiliense oil and the placebo group with application of mineral oil. After sacrifice, in seven fourteen days after surgery, skin samples were subjected to tensile-histological analysis. Results: There was a significant intergroup difference in the maximum strength of traction, as well as an increase in collagen synthesis in the area of lesions in the treated group. Conclusion: Treatment with oil from Caryocar brasiliense increases the tensile strength of the skin, improving the healing response and reducing the risks of dehiscence and postoperative complications.

Engineering D-Amino Acid Containing Collagen Like Peptide at the Cleavage Site of Clostridium histolyticum Collagenase for Its Inhibition.

Collagenase is an important enzyme which plays an important role in degradation of collagen in wound healing, cancer metastasis and even in embryonic development. However, the mechanism of this degradation has not yet been completely understood. In the field of biomedical and protein engineering, the design and development of new peptide based materials is of main concern. In the present work an attempt has been made to study the effect of DAla in collagen like peptide (imino-poor region of type I collagen) on the structure and stability of peptide against enzyme hydrolysis. Effect of replacement of DAla in the collagen like peptide has been studied using circular dichroic spectroscopy (CD). Our findings suggest that, DAla substitution leads to conformational changes in the secondary structure and favours the formation of polyproline II conformation than its L-counterpart in the imino-poor region of collagen like peptides. Change in the chirality of alanine at the cleavage site of collagenase in the imino-poor region inhibits collagenolytic activity. This may find application in design of peptides and peptidomimics for enzyme-substrate interaction, specifically with reference to collagen and other extra cellular matrix proteins.

Preparation of differently sized injectable collagen micro-scaffolds.

Collagen scaffolds have been widely used as biomaterials for tissue engineering. In general, application of scaffolds requires surgery. In this study, we describe a new and simple technique to prepare porous micro-scaffolds from type I collagen fibrils which can be injected, thus preventing surgery. The size of the micro-scaffolds could be easily controlled using sieves with varying cut-offs. EDC-NHS crosslinking was essential to stabilize the collagen micro-scaffolds. Micro-scaffolds were highly porous and could be injected through small diameter needles (18-21 gauge). Collagen micro-scaffolds may be used as injectables for the local delivery of effector molecules and/or cells, thus creating specific niches to enhance local tissue regeneration.

Engineering of implantable cartilaginous structures from bone marrow-derived mesenchymal stem cells.

Fabrication of implantable cartilaginous structures that could be secured in the joint defect could provide an alternative therapeutic approach to prosthetic joint replacement. Herein we explored the possibility of using biodegradable hydrogels in combination with a polyglycolic acid (PGA) scaffold to provide an environment propitious to mesenchymal stem cells (MSCs) chondrogenic differentiation. We examined the influence of type I collagen gel and alginate combined with PGA meshes on the extracellular matrix composition of tissue-engineered transplants. MSCs were isolated from young rabbits, expanded in monolayers, suspended in each hydrogel, and loaded on PGA scaffolds. All constructs (n=48) were cultured in serum-free medium containing transforming growth factor beta-1, under dynamic conditions in specially designed bioreactors for 3-6 weeks. All cell-polymer constructs had a white, shiny aspect, and retained their initial size and shape over the culture period. Their thickness increased substantially over time, and no shrinkage was observed. All specimens developed a hyalin-like extracellular matrix containing glycosaminoglycans (GAGs) and type II collagen, but significant differences were observed among the three different groups. In PGA/MSCs and collagen-PGA/MSCs constructs, the cell growth phase and the chondrogenic differentiation phase of MSCs occurred during the first 3 weeks. In alginate-PGA/MSCs constructs, cells remained round in the hydrogel and cartilage extracellular matrix deposition was delayed. However, at 6 weeks, alginate-PGA/MSCs constructs exhibited higher contents of GAGs and lower contents of type I collagen. These results suggest that the implied time for the transplantation of in vitro engineered constructs depends, among other factors, on the nature of the scaffold envisioned. In this study, we demonstrated that the use of a composite hydrogel-PGA scaffold supported the in vitro growth of implantable cartilaginous structures cultured in a bioreactor system.

Rapid synthesis of a register-specific heterotrimeric type I collagen helix encompassing the integrin alpha2beta1 binding site.

We report a rapid method to synthesize cystine cross-linked heterotrimeric collagenous peptides. They can be engineered to favour one particular axial alignment of the strands, called the register of the helix. Here, the sequence of the constituent peptides contains 18 residues of "guest" collagen type I sequence flanked by N and C-terminal (Gly-Pro-Pro)5 "host" modules which ensure helicity. Further C-terminal residues include appropriately spaced cysteine residues and alanine to provide the necessary flexibility for helix formation. The cross-linking reaction and subsequent separation protocols have been designed for any inserted collagen sequence that does not contain a cysteine residue. Mass spectrometry and ion-exchange chromatography allow us to distinguish between different disulphide-bonded species and to monitor the formation of side-products. Starting peptide can be recovered simply from the reaction mixture by reduction and separation. Yields are typically 30%, working on a 10 mg scale. 15N-1H NMR and platelet adhesion studies show that the peptide heterotrimers presented here can reshuffle to cover all three axial registers. Less flexible spacers between the disulphide linkages and the helix will restrict each heterotrimer to one register only.