Search Results (5)

Background: Autologous fat grafting is widely used in reconstructive, aesthetic and regenerative surgery and often requires repeated applications. Cryopreservation of lipoaspirate enables autologous fat banking and off-the-shelf availability; however, its clinical implementation is limited by freezing-induced tissue injury, regulatory requirements and uncertainties regarding the optimal preservation protocol. Glycerol is a biocompatible cryoprotective agent with promising preliminary data. Nevertheless, the optimal concentration for lipoaspirate cryopreservation remains unknown. The aim of this study was to determine the optimal glycerol concentration for preservation of adipose tissue processed according to the Cell-Enriched Lipotransfer (CELT) protocol in clinically relevant volumes under GMP-compatible conditions. Methods: Lipoaspirates from 10 patients were processed by centrifugation according to the CELT protocol and allocated into experimental groups: fresh unfrozen control, frozen samples without cryoprotectant, frozen samples with PBS, and frozen samples supplemented with glycerol in concentrations ranging from 10% to 60%. Samples were cryopreserved using a controlled freezing rate at a temperature of −80 °C for 24 h. Large-volume cryopreservation was additionally performed with the best concentration of glycerol. Post-thaw tissue quality was assessed by resazurin assay of whole tissue, stromal vascular fraction (SVF) cell live/dead counting, and resazurin assay after short-term cell culture. Results: Glycerol supplementation improved post-thaw tissue viability compared with cryopreservation without cryoprotectant or with PBS alone. An optimal concentration range between 10% and 30% glycerol was identified, with highest preservation of metabolic activity and surviving cell yield observed at 20%. Higher glycerol concentrations resulted in a marked decline in tissue quality. Cryopreservation in large volume was feasible and did not impair post-thaw viability compared with small-volume samples. Conclusions: Glycerol-based cryopreservation allows effective and GMP-compatible preservation of human lipoaspirate. An optimal glycerol concentration range was identified, enabling large-volume fat banking without compromising tissue quality. This protocol provides a clinically applicable strategy for autologous fat storage and may facilitate repeated reconstructive and regenerative treatments. Full article

Background: Mechanical processing techniques are commonly employed to prepare adipose tissue for clinical applications in reconstructive and aesthetic procedures. However, their histological and immunohistochemical impact on adipose tissue remains incompletely characterized. Purpose: This systematic review aims to investigate the impact of mechanical processing on the histological and immunohistochemical properties of adipose tissue. Methods: A systematic search was conducted using PubMed, Ovid, and Cochrane Library databases, with publications up to December 2024, employing Boolean operators (“mechanically processed” OR “lipoaspirate” OR “fat graft” OR “gauze rolling” OR “decantation” OR “coleman fat” OR “celt” OR “nanofat” OR “lipofilling” OR “human fat”) AND (“histol*”). Included were English-language studies or studies with a recognized English translation which had been subject to peer review and reported quantitative or qualitative markers of mechanically processed human adipose tissue with histology or immunohistochemistry. Risk of Bias was assessed with the OHAT score. Results: A total of 15 studies (n = 15) were included. In 13 of 15 studies (87%), mechanically processed adipose tissue demonstrated an increased stromal vascular fraction (SVF) cell density compared to unprocessed fat. Twelve studies (80%) reported improved preservation of the extracellular matrix (ECM), while 11 studies (73%) observed a reduction in mature adipocytes. Immunohistochemical analyses in 10 studies (67%) revealed elevated expression of vascular markers (CD31, CD34) and perilipin. Adverse histological features such as oil cysts, fibrosis, and inflammatory infiltrates were reduced in 9 studies (60%). Considerable heterogeneity in processing techniques and staining protocols precluded meta-analysis. Conclusions: Mechanical processing of adipose tissue is associated with favorable histological and immunohistochemical profiles, including increased SVF cell density, improved ECM preservation, and reduced inflammatory and fibrotic features. These findings support the potential of mechanical processing to enhance graft quality; however, standardization of techniques and evaluation protocols is needed to strengthen clinical translation. Full article

Lipofilling has far more applications than cosmetic surgery alone. Due to its high content of stromal vascular fraction (SVF) cells, lipoaspirate can also be used to treat wounds, as its cellular components may accelerate wound healing. Using our CELT^PLUS protocol, we can increase the number of SVF cells per volume. Unfortunately, some patients require more than one treatment to achieve an optimal outcome, but would unnecessarily suffer from repeated liposuction. Therefore, our objective was to test whether cryopreserving CELT^PLUS fat could offer a solution, potentially avoiding the need for repeated liposuction procedures. DMSO was used as a cryoprotective agent for proof-of-principle testing, although other non-toxic cryoprotective agents should be considered in the future. The rest of our freezing protocol is a clinically friendly attempt to facilitate the translation into clinical practice. We tested the cryopreserved tissue using histological evaluation, metabolism measurement, SVF cell yield estimation, PCRs from both whole tissue and from cultured SVF cells, and Oil Red “O” staining. We found that freezing CELT^PLUS fat with DMSO yields better results than without cryoprotection in all evaluated methods. Until non-toxic cryoprotective agents are tested on CELT^PLUS fat, we do not recommend initiating animal or human testing. Full article

Background: Histological and immunohistochemical analyses of adipose tissue are essential for evaluating the quality and functionality of lipoaspirates in regenerative medicine and fat grafting procedures. These methods provide insights into tissue viability, cellular subtypes, and extracellular matrix (ECM) composition—all factors influencing graft retention and clinical outcomes. Purpose: This scoping review aims to summarize the most commonly used staining methods and their applications in the histology and immunohistochemistry of adipose tissue. By exploring qualitative and quantitative markers, we seek to guide researchers in selecting the appropriate methodologies for addressing experimental and translational research. Methods: A systematic search was conducted using PubMed, Ovid, and the Cochrane Library databases from inception to 2024, employing Boolean operators (“lipoaspirate” OR “fat graft” OR “gauze rolling” OR “decantation” OR “coleman fat” OR “celt” OR “nanofat” OR “lipofilling” OR “human fat” AND “histol*”). Studies were included if they utilized histology or immunohistochemistry on undigested human adipose tissue or its derivatives. The inclusion criteria focused on peer-reviewed, English-language studies reporting quantitative and qualitative data on adipose tissue markers. Results: Out of 166 studies analyzed, hematoxylin–eosin (H&E) was the most frequently employed histological stain (152 studies), followed by Masson Trichrome and Sudan III. Immunohistochemical markers such as CD31, CD34, and perilipin were extensively used to distinguish stromal vascular fraction (SVF) cells, adipocytes, and inflammatory processes. Studies employing semiquantitative scoring demonstrated enhanced comparability, particularly for fibrosis, necrosis, and oil cyst evaluation. Quantitative analyses focused on SVF cell density, mature adipocyte integrity, and ECM composition. Methodological inconsistencies, particularly in preparation protocols, were observed in 25 studies. Conclusions: This review highlights the critical role of histological and immunohistochemical methods in adipose tissue research. H&E staining remains the cornerstone for general tissue evaluation in the clinical context, while specialized stains and immunohistochemical markers allow for detailed analyses of specific cellular and ECM components in experimental research. Standardizing preparation and evaluation protocols will enhance interstudy comparability and support advancements in adipose tissue-based therapies. Full article

Autologous lipotransfer is a promising method for tissue regeneration, because white adipose tissue contains a heterogeneous cell population, including mesenchymal stem cells, endothelial cells, immune cells, and adipocytes. In order to improve the outcome, adipose tissue can be processed before application. In this study, we investigated changes caused by mechanical processing. Lipoaspirates were processed using sedimentation, first-time centrifugation, shear-force homogenization, and second-time centrifugation. The average adipocyte size, stromal vascular cell count, and adipocyte depot size were examined histologically at every processing step. In addition, the adipose derived stem cells (ADSCs) were isolated and differentiated osteogenically and adipogenically. While homogenization causes a disruption of adipocyte depots, the shape of the remaining adipocytes is not changed. On average, these adipocytes are smaller than the depot adipocytes, they are surrounded by the ECM, and therefore mechanically more stable. The volume loss of adipocyte depots leads to a significant enrichment of stromal vascular cells such as ADSCs. However, the mechanical processing does not change the potential of the ADSCs to differentiate adipogenically or osteogenically. It thus appears that mechanically processed lipoaspirates are promising for the reparation of even mechanically stressed tissue as that found in nasolabial folds. The changes resulting from the processing correspond more to a filtration of mechanically less stable components than to a manipulation of the tissue. Full article