M. I. V. Viloria

Eletroterapia no processo de reparação da superfície articular de coelhos

The effects of postooperative electrotherapy in the repair of full-thickness osteochondral defects in the troclear groove of 36 adult rabbits were evaluated histologically. In the control group, granulation tissue was present two weeks post-operatively (PO); hyaline cartilage was observed at four and at seven weeks PO; subchondral bone regeneration was limited to the deeper portions of the defects at seven weeks PO. In group I (stimulated daily), granulation tissue presented abundant vascularization at two weeks PO and the repair tissue remained undifferentiated superficially, with formation of new subchondral bone up to the level of the original osteochondral junction, at seven weeks PO. The animals in group II (stimulated every other day), responded in two ways: through repair with hyaline cartilage, with reduced osteogenesis, similar to control group; or undifferentiated tissue, with an intense osteogenesis, as in group I. The postoperative electrical stimulation inhibited the tissue differentiation into hialine cartilage. On the other hand, endochondral ossification was accelerated, with complete regeneration of subchondral bone, in treated animals. In view of the importance of the subchondral bone for the integrity of the repair tissue, electrical stimulation is benefic in the initial fase (four weeks) of osteochondral defects repair.

Auto-enxerto percutâneode medula óssea: II. reparação de falhas segmentares produzidas no rádio de coelhos

In order to study the whole and concentrated bone marrow grafted percutaneously in order to repair produced osseous defects, it was used 16 male White New Zealand rabbits, aged between 5 and 6 months, average body weight of 3.5kg, set apart in groups I and II. In both groups it was produced a radial bilateral defects by the removal of an 1-cm osteal-periosteal segment. Percutaneous grafting was performed 5 days after surgery. In group I, each animal received 1.0ml of whole bone marrow in one radius (treatment) immediately after iliac crest aspiration and in group II, after aspiration and centrifuging of 2.0ml of bone marrow, it was administrated 1.0ml of the sediment in one radius (treatment). In both groups it was administered 1.0ml of physiological saline solution in the contralateral radius (control). Radiographic evaluation, performed every 7 days for 5 weeks, showed that percutaneous bone marrow grafting resulted in precocious radiopacity of the region of the osseous defect in both groups when comparing to the control, being characterized by circumscribed and well defined areas in the middle of the defect. Bone formation of the control radii initiated from the extremities in direction to the middle of the defect. Concentration of medullary cells by centrifuging does not negatively interfere in the osteogenic potential of the sample. This osteogenic potential of the bone marrow graft occurs mostly after the first and second weeks post-grafting, which was evidenced by the difference of radiographic images in this period and tendency to uniformity. Microscopically, the grafted radii were in a different repair stage in relation to the control, but at 5 weeks there were more histological similarities than differences.

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

Platelet rich plasma associated with heterologous fresh and thawed chondrocytes on osteochondral lesions of rabbits

Cultivaram-se condrocitos obtidos da articulacao do joelho de coelhos. Metade das celulas foi mantida em cultura para posterior implantacao, e a outra metade foi congelada durante seis meses com a finalidade de avaliar a viabilidade. Criou-se um defeito circular osteocondral no joelho direito de outros vinte e sete coelhos. O grupo controle (GC) nao recebeu tratamento. Os grupos descongelado (TH) e fresco (FH) receberam, respectivamente, implantes heterologos de condrocitos cultivados descongelados e frescos, associados com PRP. O grupo GC apresentou maior dor e claudicacao em comparacao com os outros grupos aos sete dias apos o implante. Microscopicamente, aos 45 e 90 dias, os grupos TH e FH mostraram preenchimento da falha com tecido cartilaginoso contendo condrocitos circundados por uma matriz densa de glicosaminoglicanos. Nesse periodo, no grupo CG, a cura ocorreu com tecido conjuntivo fibroso vascularizado e sem integracao com o osso subcondral. Condrocitos heterologos criopreservados foram viaveis para implantacao e tratamento de lesoes osteocondrais; a associacao com o PRP permitiu a fixacao de celulas na lesao e ofereceu fatores de crescimento que aceleraram a reparacao com o tecido semelhante a cartilagem hialina articular.