The obesity epidemic and its associated co-morbidities present a looming challenge to health care delivery throughout the world. Obesity is characterized as a sterile inflammatory process within adipose tissues leading to dysregulated secretion of bio-active adipokines such as adiponectin and leptin as well as systemic metabolic dysfunction. The majority of current obesity research has focused primarily on pre-clinical animal models in vivo and two-dimensional (2D) cell culture models in vitro. Neither of these generalized approaches is optimal due to inter-species variability, insufficient accuracy with respect to predicting human outcomes, and failure to recapitulate the three-dimensional (3D) microenvironment. Consequently, there is a growing demand and need for more sophisticated microphysiological systems (MPS) in order to re-produce more physiologically accurate human white and brown/beige adipose depots. To address this research need, human and murine cell lines and primary cultures are being combined with bioscaffolds to create functional 3-dimensional environments that are suitable for metabolically active adipose organoids in both static and perfusion bioreactor cultures. The development of these technologies will have considerable impact on the future pace of discovery for novel small molecules and biologics designed to prevent and treat metabolic syndrome and obesity in humans. Furthermore, when these adipose tissue models are integrated with other organ systems they will have applicability to obesity-related disorders such as diabetes, non-alcoholic fatty liver disease, and osteoarthritis.

Introduction: Adipose derived stromal/stem cells (ASCs) hold potential as cell therapeutics for a wide range of disease states; however, many expansion protocols rely on the use of fetal bovine serum (FBS) as a cell culture nutrient supplement. The current study explores the substitution of lysates from expired human platelets (HPLs) as an FBS substitute. Methods: Expired human platelets from an authorized blood center were lysed by freeze/thawing and used to examine human ASCs with respect to proliferation using hematocytometer cell counts, colony forming unit-fibroblast (CFU-F) frequency, surface immunophenotype by flow cytometry, and tri-lineage (adipocyte, chondrocyte, osteoblast) differentiation potential by histochemical staining. Results: The proliferation assays demonstrated that HPLs supported ASC proliferation in a concentration dependent manner, reaching levels that exceeded that observed in the presence of 10% FBS. The concentration of 0.75% HPLs was equivalent to 10% FBS when utilized in cell culture media with respect to proliferation, immunophenotype, and CFU-F frequency. When added to osteogenic, adipogenic, and chondrogenic differentiation media, both supplements showed appropriate differentiation by staining. Conclusion: HPLs is an effective substitute for FBS in the culture, expansion and differentiation of human ASCs suitable for pre-clinical studies; however, additional assays and analyses will be necessary to validate HPLs for clinical applications and regulatory approval.

Obesity, defined as a body mass index of 30 kg/m² or above, has increased considerably in incidence and frequency within the United States and globally. Associated comorbidities including cardiovascular disease, type 2 diabetes mellitus, metabolic syndrome, and nonalcoholic fatty liver disease have led to a focus on the mechanisms promoting the prevention and treatment of obesity. Commonly utilized in vitro models employ human or mouse preadipocyte cell lines in a 2-dimensional (2D) format. Due to the structural, biochemical, and biological limitations of these models, increased attention has been placed on “organ on a chip” technologies for a 3-dimensional (3D) culture. Herein, we describe a method employing cryopreserved primary human stromal vascular fraction (SVF) cells and a human blood product-derived biological scaffold to create a 3D adipose depot in vitro. The “fat-on-chip” 3D cultures have been validated relative to 2D cultures based on proliferation, flow cytometry, adipogenic differentiation, confocal microscopy/immunofluorescence, and functional assays (adipokine secretion, glucose uptake, and lipolysis). Thus, the in vitro culture system demonstrates the critical characteristics required for a humanized 3D white adipose tissue (WAT) model.

Background: Precise flap planning and perforator selection are paramount for successful perforator flap surgery. Portable color-flow ultrasound (PCFU) is a convenient, low-cost, easily accessible imaging modality that is pivotal in the planning of perforator flaps where anatomic variability is the rule. Methods: Perforator mapping was performed using an L12–4 linear-array ultrasound probe connected to an Android tablet. Images were obtained with the Lumify app (Philips Lumify, usa.philips.com). Perforator characteristics were recorded (arterial diameter, emergence points from fascia, subcutaneous course, and projection onto the skin surface) using still images and real-time videos. Results: Thirty consecutive patients had 40 perforator or musculocutaneous flap reconstructions over a 2-year period. For the 15 flaps that had preoperative computed tomographic angiography (CTA) imaging, the preoperative sonographic measurements correlated with CTA and intraoperative findings. Portable color-flow ultrasound allowed perforator flap design and selection based on the largest available perforator, the most appropriate flap thickness, and comparison of multiple donor sites including left versus right. Two deep inferior epigastric perforator patients required take-back to the operating room for debridement of devitalized nonflap tissue. The superior gluteal artery perforator flap was abandoned intraoperatively due to proximal vascular anomalies. Overall flap success rate was 98% (39/40 flaps). Conclusions: Our experience with PCFU has rapidly improved, allowing individualized perforator flap selection and design based on each patient's unique perforator anatomy, reconstructive requirements, and donor site characteristics. In our practice, PCFU has supplemented CTA and in many cases has supplanted CTA as the primary imaging modality of choice in the planning of perforator flap reconstruction.