Betânia Souza Monteiro

Células-tronco mesenquimais

Of all the stem cells studied so far, the mesenchymal stem cells (MSC) stand out for their high plasticity and capacity of generating mesodermal and non-mesodermal tissues. In addition, immunomodulatory and immunosuppressive features that expand possibilities for therapeutic use are present in these cells. A variety of pro and anti-inflammatory cytokines and growth factors are secrete for MSC and provide a modulation of inflammatory response, re-establishment of vascular supply and adequate repair of the tissue, contributing to tissue homeostasis under physiologic conditions. Therefore, they can induce secretion of soluble factors that stimulate their differentiation by other cells present at the niches tissue, promoting the repair process. Cell therapy using MSC is a promises therapeutic alternative, but understanding the biology of these cells is still under construction. The aim of the article is to conduct a short review of these undifferentiated mesenchymal cells.

Differentiation of adipose tissue-derived mesenchymal stem cells into cardiomyocytes

BACKGROUND Cardiomyocytes have small potential for renovation and proliferation in vivo. Consequently, the heart muscle has limited capacity of self-renewal. Mesenchymal stem cells (MSC) therapy, as well as MSC differentiated into cardiomyocytes, has been used in the attempt to minimize the effects of ischemic-hypoxic lesions and those affecting the electrical conduction system of the heart. OBJECTIVE The present study compared three distinct protocols for induced differentiation of MSC into cardiomyocytes aimed at finding a viable method for producing a large number of functional cells expressing cardiomyogenic phenotype. METHODS Mesenchymal stem cells were obtained from the adipose tissue of young transgenic Lewis rats expressing green fluorescent protein (GFP), and submitted to three distinct differentiation-inducing media: 1) Planat-Bérnard, 2) 5-azacytidine, and 3) Planat-Bérnard + 5-azacytidine; further, these cells were identified based on the expression of cardiac cell markers. RESULTS All three protocols detected the expression of sarcomeric-alpha-actinin protein in the exoskeleton of cells, expression of connexin-43 in the nuclear and cytoplasmic membrane, and formation of gap junctions, which are necessary for electrical impulse propagation in the myocardium. However, no spontaneous cell contraction was observed with any of the tested protocols. CONCLUSION Induction with 5-azacytidine provided an effective cadiomyogenic cellular differentiation similar to that obtained with Planat-Bénard media. Therefore, 5-azacytidine was the method of choice for being the simplest, fastest and lowest-cost protocol for cell differentiation.

Role of autologous mesenchymal stem cells associated with platelet-rich plasma on healing of cutaneous wounds in diabetic mice

Background. Chronic cutaneous lesions affect 15% of human patients with diabetes, and the associated risk of limb amputations is 15–46 times greater than that of people with normal glycaemia. It is estimated that half of these limb amputations could be avoided by opportune treatment with somatic stem cells or platelet‐rich plasma (PRP).

Association of mesenchymal stem cells with platelet rich plasma on the repair of critical calvarial defects in mice

PURPOSE To evaluate the effects of mesenchymal stem cells (MSC) from eight mice C57BL/6 gfp(+) bone marrows expanded in cultures associated with platelets rich plasma (PRP) deriving from another eight mice, in the repair of critical defects in calvarial bone produced in twenty-four adult isogenic mice C57BL/6. METHODS The animals were submitted to a cranial defect of 6.0mm in diameter and divided into two equal experimental groups. Control group did not receive treatment and the treated group received a MSC pellet containing 1.0 x 10(7) cells/mL associated with 50.0 µL of plasma gel containing 1.0 x 10(9) autologous platelets within the defect. RESULTS In the treated group was observed process of angiogenesis and bone repair better than control group. CONCLUSION Mesenchymal stem cells derived from bone marrow of C57BL/6 gfp(+) mice associated with PRP gel applied in bone critical defects produced in calvarial contributes positively to the process of bone repair.

Plasma rico em plaquetas associado ou não ao osso esponjoso autógeno no reparo de falhas ósseas experimentais

The present study evaluated autogenous platelet rich plasmas (PRP) influence on the reparation process of four bone defects made on rabbits skull, associated or not to autogenous bone graft (EOE). Defect I received PRP only; defect II received 3mg of EOE only; defect III received EOE associated to PRP; defect IV was left to heal naturally, serving as control. After each surgery the animals were randomly divided into three groups that were euthanized at 30, 60 and 90 days. In the mesoscopic evaluation bone ingrowth started from the defects borders to the center and from the bottom to the surface for all observation times on the control (VI) and PRP only (I) groups. In the groups treated with EOE only (II) and EOE associated to PRP (III) new bone was observed in the center of the defects. Radiographic analysis showed greater central radiopacity for groups treated with EOE only (II) and EOE associated to PRP (III) at all observation times. Microscopically in the group treated with EOE associated to PRP (III) at 30 days the graft was indistinguishable from new bone present on the border of the defect, associated to a moderate quantity of a very vascularized and cellular fibrous connective tissue. This tissue showed an extracelular eosinophilic amorphous foamy material, associated to an inflammatory process constituted by lymphocytes and in less number by macrophages and multinucleated giant cells that may have negatively influenced early bone formation. At 60 and 90 days occasional spots of lymphocytic inflammation were observed. Both treatments, PRP associated or not to EOE, were similar for the bone ingrowth at the final time of observation; the graft used alone determined early bone reparation and thromboplastine used for the platelet gel formation incited a foreign body-like reaction that acted negatively on the initial reparation.

Polímero derivado de mamona acrescido de cálcio, associado ou não à medula óssea autógena na reparação de falhas ósseas

In order to evaluate tissue repair after the use of castor oil polymer implant additioned with 40% sodium carbonate, isolated or associated to autogenous bone marrow in heterotopic site and in experimental bone gaps in radii of rabbits, 30 White New Zealand rabbits were submitted to bilateral radial ostectomy. In 15 rabbits the bone gap of the right side was filled with polymer cylinders (group P) of similar size of the gaps; the remaining rabbits received autogenous bone marrow with the implant (group M). The bone defects of the left limb did not receive any treatment and served as control. Six rabbits received 6 implants in the Rectus abdominus muscle (heterotopic site) and in three of these rabbits the implants was associated with bone marrow. In the radiographic study both groups presented increased radiopacity at the implant site without bone axis deviation or resorption of the receptor bone ends. Group P presented irregular calcification areas at the peripheral region and over the polymer. Group M presented a more intense, regular and precocious radiopacity pattern in relation to group P. In microscopical evaluation there was evidence of immature bone tissue formation tending to organize itself, isolated sprouts of neoformed bone over the polymer and its superficial pores. It was concluded that implant allows osteogenenesis and osteoconduction in bone gaps, and bone formation was progressive, especially when additioned bone marrow aspirate; there was capillary, perivascular tissue and osteoprogenitor cells migrating into the pores; with fibrovascular tissue permeating implant surface; implants incorporation was slowly and was found incomplete until 9 weeks; the implant was able to induce foreign body reaction without toxic or secondary reactions to its presence. In heterotopic and orthotopic sites, the implant was not able to induce bone formation, inciting mild foreign-body reaction with giant cells and surrounding fibrous layer.

Propriedades mecânicas de meniscos frescos de coelhos e preservados em glicerina 98

The present study evaluated the compressive strength of medial menisci of New Zealand rabbits, through mechanical compression test. Thirty menisci were distributed in three groups: group MF, composed by ten fresh menisci; MG group, composed by ten menisci preserved in 98% glycerin for 30 days; and, group MR, ten menisci preserved in 98% glycerin for 30 days and rehydrated in NaCl 0.9% for 12 hours. The menisci in each group were submitted to compression test in the perpendicular direction to the anatomical plane and had the elasticity limit, the elastic deformity, the rupture stress point and the stiffness index evaluated. The menisci from the preserved groups MG and MR had the elastic limit similar to the fresh menisci group (MF). The group of menisci preserved in glycerin (MG) presented lower elastic deformity capacity (P<0.05) if compared to the other groups, MF and MR, and a higher tension capacity at elastic limit. The menisci from group (MG) presented higher stiffness (P<0.05) than the ones in the MF and MR groups. It can be concluded that the group menisci preserved in glycerin 98% followed by rehydration in Nacl 0,9% (MR), did not showed any significant alterations in the capacity of the menisci elastic limit.

Estrutura e celularidade de meniscos frescos de coelhos (Oryctolagus cuniculus) preservados em glicerina

In the present study was evaluated the tissue architecture, the percentage of cellular population, as well as viability and distribution of cells in fresh menisci of rabbits and preserved in 98% glycerin. Were analyzed medial menisci of rabbits freshly slaughtered, which were distributed into three groups: the MF group (n=7), composed of fresh menisci, corresponded to the control group; the MG group (n=7), composed by menisci preserved in 98% glycerin, for 30 days, and the MR group (n=7) by menisci preserved in 98% glycerin and rehydrated in NaCl 0.9% for 12 hours. In all menisci were identified and quantified the different cell types: fibroblasts/fibrocytes and condrocytes. The cell population percentage was statistically similar in all groups. All menisci preserved in the MG and MR groups showed a lower intensity of color and shrinkage of collagen fibers, reduced volume and higher intensity of staining of nucleus (chromatin condensation), as compared to fresh menisci (MF), featuring the phenomenon of cell lysis. The cartilaginous matrix of preserved menisci proved to be well preserved because the tissue architecture was maintained. It was concluded that 98% glycerin is an optional preservation mean for meniscal allografts with a devitalized collagenous matrix.

Hemogasometria em cães com desidratação experimental tratados com soluções eletrolíticas comerciais administradas por via intravenosa

Three commercial intravenous electrolyte solutions were compared as for their effects on the blood acid-base status in dogs experimentally dehydrated by withholding water and inducing polyuria. Animals were randomly divided into three groups which were rehydrated with the following commercial electrolyte solutions during 12 hours: Lactate Ringer´s solution (RL), Ringer´s solution (RS) and a normal saline solution (0.9% sodium chloride) containing 5% dextrose (GF). The RL´s intravenous fluid therapy resulted in an alkalinizing effect demonstrated by a mild increase in arterial blood pH, ctCO2, bicarbonate (cHCO-3), and arterial blood base concentration (cBase) and, thus, can be used in animals exhibiting mild to moderate metabolic acidosis. In contrast, the RS and GF therapies led to a mild decrease in the concentration of arterial blood tritiable base (cBase) inducing an acidifying effect, which make them an option to treat dogs with metabolic alkalosis.

Efeitos do congelamento sobre condrócitos cultivados de coelhos

Avaliaram-se os efeitos do congelamento sobre condrocitos mantidos em cultura, com o objetivo de se estabelecer um banco celular para futura aplicacao como implante heterologo. Condrocitos extraidos da cartilagem articular de nove coelhos saudaveis, da raca Nova Zelândia Branca, foram cultivados e submetidos ao congelamento, com o citoprotetor sulfoxido de dimetila a 5%, por um periodo de seis meses. Analises fenotipicas e de microscopia eletronica de varredura foram realizadas com o objetivo de identificar diferencas morfologicas e funcionais entre as celulas frescas e as descongeladas. Apos a digestao enzimatica, foram obtidas 4,8x105 celulas por coelho. Os condrocitos frescos apresentaram elevada taxa mitotica e abundante presenca de matriz ate os 60 dias de cultura. Nas culturas dos condrocitos descongelados, a perda de estabilidade fenotipica foi marcante, o que foi demonstrado pela baixa intensidade da coloracao dos proteoglicanos e pela fraca imunomarcacao do colageno tipo II. Sob as condicoes de congelamento utilizadas, houve importante perda de viabilidade condrocitica. Para futuros estudos in vivo de implante heterologo, estes resultados sugerem que o elevado numero de celulas deve ser implantado no sitio hospedeiro, com o objetivo de se obter maior quantidade de celulas viaveis, e que os condrocitos deverao ser implantados com duas semanas de cultivo, periodo em que apresentam melhor taxa de viabilidade