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Background Scaffolds have considerably advanced in recent years. In orthopaedic surgery, scaffolds have been used as grafts in procedures involving tendon and ligament reconstruction. This paper aimed to produce and evaluate decellularized tendon scaffolds (DTSs) from biomechanical, microscopic, macroscopic and in vivo perspectives. Methods Bilateral gastrocnemius muscle tendons from 18 adult New Zealand rabbits were collected. Of these 36 tendons, 11 were used as controls (Group A - control), and 25 were used in the decellularization protocol (Group B - DTS). The groups were subjected to histological, biomechanical and macroscopic analyses, and Group B - DTS was subjected to an additional in vivo evaluation. In the decellularization protocol, we used a combination of aprotinin, ethylenediamine tetraacetic acid (EDTA), sodium dodecyl sulfate (SDS) and t-octyl-phenoxypolyethoxyethanol (Triton X-100) for six days. During this period, the scaffolds were kept at room temperature on an orbital shaker with constant motion. Results The DTSs showed an increased cross-sectional area and inter-fascicular distance and no change in parallelism or matrix organization. The nuclear material was not organized in the DTSs as it was in the control. In the biomechanical analysis, no significant differences were found between the groups after analysing the ultimate tensile load, stiffness, and elongation at the ultimate tensile load. During the in vivo evaluation, mononuclear cell infiltration was noted. Conclusions The evaluated decellularization protocol generated a tendon scaffold, maintained the most important biomechanical characteristics and permitted cell infiltration.

Human adipose tissue has been described as a potential alternative reservoir for stem cells. Although studies have been performed in rabbits using autologous adipose-derived stem cells (ADSC), these cells have not been well characterized. The primary objectives of this study were to demonstrate the presence of adipose-derived stem cells isolated from rabbit inguinal fat pads and to characterize them through osteogenic and adipogenic in vitro differentiation and lipid fingerprinting analysis. The secondary objective was to evaluate cell behavior through growth kinetics, cell viability, and DNA integrity. Rabbit ADSCs were isolated to determine the in vitro growth kinetics and cell viability. DNA integrity was assessed by an alkaline Comet assay in passages 0 and 5. The osteogenic differentiation was evaluated by Von Kossa, and Alizarin Red S staining and adipogenic differentiation were assessed by Oil Red O staining. Lipid fingerprinting analyses of control, adipogenic, and osteogenic differentiated cells were performed by MALDI-TOF/MS. We demonstrate that rabbit ADSC have a constant growth rate at the early passages, with increased DNA fragmentation at or after passage 5. Rabbit ADSC viability was similar in passages 2 and 5 (90.7% and 86.6%, respectively), but there was a tendency to decreased cellular growth rate after passage 3. The ADSC were characterized by the expression of surface markers such as CD29 (67.4%) and CD44 (89.4%), using CD 45 (0.77%) as a negative control. ADSC from rabbits were successfully isolated form the inguinal region. These cells were capable to differentiate into osteogenic and adipogenic tissue when they were placed in inductive media. After each passage, there was a trend towards decreased cell growth. On the other hand, DNA fragmentation increased at each passage. ADSC had a different lipid profile when placed in control, adipogenic, or osteogenic media.

The use of Adipose‐Derived Stem Cells (ADSC) has been presented as a new alternative for tendon reconstruction. Have been admitted that ADSCs are related to better outcomes when used in tendon healing. This research was designed to apply the potential of ADSCs in tendon healing. Flexor digitorum superficialis tendon lesion was performed on both legs of eleven New Zealand rabbits and them, at the same time, treated as follows: Suture alone (Group III − Suture, n:10), suture associated with ADSC (Group IV − Suture + ADSC, n:10) or without suture (Group II − SHAN, n:2). At four weeks after the tendon surgery, the animal was euthanized, and the tendon evaluated (biomechanically and macroscopically). We used 5 additional New Zealand rabbits in the control group “Group I − Control, n:10”. In the macroscopic evaluation, the group with ADSC presented a more homogeneous gross morphology compared with the group III. Biomechanical testing showed a lower ultimate tensile load, stiffness and a higher cross‐sectional area in the group III and IV compared with the control group. The group with ADSC showed a greater ultimate tensile load, a larger cross‐sectional area and bigger deformation at the ultimate tensile load when compared to the group without ADSC. In general terms, the use of ADSCs in tendon healing have biomechanical advantages compared to the non‐use of ADSCs at 4 weeks after surgery. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1281–1286, 2019.

Resumo Objetivo Mensuração semiquantitativa e automatizada da remoção de material nuclear e da infiltração celular em scaffolds tendinosos descelularizados (STDs). Método Foram utilizados 16 coelhos Nova Zelândia puros, sendo o tendão do músculo gastrocnêmio coletado bilateralmente de metade destes animais (16 tendões coletados); 4 foram mantidos como controle e 12 foram submetidos ao protocolo de descelularização (STD). Dos STDs, 8 foram utilizados como implante in vivo no modelo experimental de lesão do manguito rotador (LMR) e os restantes, assim como os controles, foram utilizados na avaliação semiquantitativa e automatizada da remoção de material nuclear. Os oito coelhos adicionais foram utilizados na confecção do modelo experimental de LMR e posterior avaliação da infiltração celular após 2 ou 8 semanas, dentro do STD. Resultados A análise semiquantitativa e automatizada utilizada demonstrou uma remoção de 79% do material nuclear (p < 0,001 e poder > 99%) e uma diminuição de 88% (p < 0,001 e poder > 99%) na área ocupada por material nuclear após o protocolo de descelularização. Sobre a infiltração celular no STD, foi observado um aumento de 256% (p < 0,001 e poder > 99%) no número de células dentro do STD na comparação entre 2 e 8 semanas de pós-operatório. Conclusão O método de mensuração semiquantitativo e automatizado proposto foi capaz de mensurar objetivamente a remoção de material nuclear e a infiltração celular no STD.