Autologous fat grafting: A comparative study of four current commercial protocols

International audienceBackground: Autologous fat grafting is a widely used technique that gives natural results when treating soft tissue deficiencies. However, there is no consensus on which is the best procedure to use, leading to unpredictable results because of fat graft resorption.Objectives: This study compared four commercial lipotransfer devices by analyzing the behavior of the processed adipose tissue and outcome of the adipose graft in an in vivo model.Methods: Four different protocols that used manual, power-assisted or water-assisted lipoas-piration and then decantation, centrifugation, or filtration were used on each of eight patients to process lipoaspirate. Harvested adipose tissue was assessed in vitro for tissue resorption, oil formation, and cytokine secretion. Graft resorption rate was calculated and histological analyses were performed after subcutaneously injecting the harvested adipose tissue in a murine model. Results: All protocols resulted in very low oil formation and histologically healthy grafts. The tissue volume was significantly greater after 2 days in culture when using manual lipoaspiration and soft centrifugations/washing steps (Microfill® /Macrofill®) compared to Water-Assisted Li-poaspiration/Decantation (BodyJet®) and Power-Assisted Lipoaspiration/Filtration (PAL® + PureGraft®). These results were confirmed in mice 1 month after subcutaneous injection , with greater efficiency obtained with protocols that used (A) manual aspiration, (B) soft centrifugations, and (C) washing steps

Autologous Fat Grafting in the Breast: Critical Points and Technique Improvements

International audienceBreast augmentation or reconstruction is a major challenge in esthetic and reconstructive surgery. While autologous fat grafting (AFG) provides a natural filler and seems easy to harvest, AFG in breast surgery is still problematic especially due to the high resorption rate associated with megavolume transfer. Despite this pending issue, there is growing interest in this method, which is becoming more and more widespread, as can be seen by the recent increase in the number of clinical studies. This review aims to highlight recent knowledge in the technique of AFG to the breast and recent refined procedures to improve fat viability and long-term success of the graft.Methods Clinical publications and trials of AFG to the breast from the past 5 years were examined. Attention was focused on the different AFG steps and the clinical out- comes, in order to highlight the strengths and weaknesses of the available protocols.Results Recent studies have concentrated on new techniques to improve fat viability and graft intake. However, all of these studies use different protocols at each step of the procedure. Furthermore, results may vary depending on the technique used for fat harvesting and processing.Conclusion This review points out the recent advances in breast AFG techniques and their associated outcomes andcomplications. The bibliography has been carefully examined to reach a consensus so that recommendations could be made for each step of the technique with the aim of improving graft viability and long-term volume maintenance

Inverse Regulation of Early and Late Chondrogenic Differentiation by Oxygen Tension Provides Cues for Stem Cell-Based Cartilage Tissue Engineering

Background/Aims: Multipotent stem/stromal cells (MSC) are considered promising for cartilage tissue engineering. However, chondrogenic differentiation of MSC can ultimately lead to the formation of hypertrophic chondrocytes responsible for the calcification of cartilage. To prevent the production of this calcified matrix at the articular site, the late hypertrophic differentiation of MSCs must be carefully controlled. Given that articular cartilage is avascular, we hypothesized that in addition to its stimulatory role in the early differentiation of chondrogenic cells, hypoxia may prevent their late hypertrophic conversion. Methods: Early and late chondrogenic differentiation were evaluated using human adipose MSC and murine ATDC5 cells cultured under either normoxic (21%O2) or hypoxic (5%O2) conditions. To investigate the effect of hypoxia on late chondrogenic differentiation, the transcriptional activity of hypoxia-inducible factor-1alpha (HIF-1α) and HIF-2α were evaluated using the NoShift DNA-binding assay and through modulation of their activity (chemical inhibitor, RNA interference). Results: Our data demonstrate that low oxygen tension not only stimulates the early chondrogenic commitment of two complementary models of chondrogenic cells, but also inhibits their hypertrophic differentiation. Conclusion: These results suggest that hypoxia can be used as an instrumental tool to prevent the formation of a calcified matrix in MSC-based cartilage tissue engineering

Comparing “intra operative” tissue engineering strategies for the repair of craniofacial bone defects

International audienceBACKGROUND:In craniofacial reconstruction, the gold standard procedure for bone regeneration is the autologous bone graft (BG). However, this procedure requiring bone harvesting is a source of morbidity. Bone substitutes, such as biphasic calcium phosphate (BCP), represent an interesting alternative but are not sufficient for bone healing in hypoplastic conditions. In such conditions, osteoprogenitors are essential to provide osteoinduction. Previous studies have shown that BCP associated with total bone marrow (TBM) provides same bone reconstruction as bone graft in a rat model of calvaria defect. Furthermore, adipose tissue stromal vascular fraction (SVF) seems to be another promising source of osteoprogenitor cells that can be used intra-operatively. This study aimed to combine, intra-operative BCP-based bone tissue engineering strategies with TBM or SVF from human sources.METHODS:5 mm critical-size calvaria defects were performed in 18 nude rat. The defects were filled with intra-operative bone tissue engineering procedures: human BG, human TBM + BCP, human SVF + BCP and, rat TBM + BCP. Animals were sacrificed 8 weeks after implantation and calvaria were processed for histological and radiological examinations. Implanted cells were labelled with a fluorochrome.RESULTS:Micro-CT analysis revealed partial repair of bone defect. Only hBG significantly succeeded in healing the defect (43.1%). However, low rate of newly formed bone tissue was observed in all tissue engineering conditions (hTBM, hSVF, ratTBM).DISCUSSION:The lack of bone formation observed in this study could possibly be attributed to the model.CONCLUSION:This study combined with a literature analysis show the stringency of the nude rat calvaria model in term of bone regeneration