Background: Centrifugation is one of the preferred methods of fat processing. Although it has been promoted for nearly three decades to separate adip

Medicine today faces the combined challenge of an increasing number of untreatable diseases and fewer drugs reaching the clinic. While pharmaceutical companies have increased the number of drugs in early development and entering phase I of clinical trials, fewer actually successfully pass phase III and launch into the market. In fact, only 1 out of every 9 drugs entering phase I will launch. In vitro preclinical tests are used to predict earlier and better the potential of new drugs and thus avoid expensive clinical trial phases. The most recent developments favor 3D cell culture and human stem cell biology. These 3D humanized models known as organoids better mimic the 3D tissue architecture and physiological cell behavior of healthy and disease models, but face critical issues in production such as small-scale batches, greater costs (when compared to monolayer cultures) and reproducibility. To become the gold standard and most relevant biological model for drug discovery and development, organoid technology needs to integrate biological culture processes with advanced microtechnologies, such as microphysiological systems based on microfluidics technology. Microphysiological systems, known as organ-on-a-chip, mimic physiological conditions better than conventional cell culture models since they can emulate perfusion, mechanical and other parameters crucial for tissue and organ physiology. In addition, they reduce labor cost and human error by supporting automated operation and reduce reagent use in miniaturized culture systems. There is thus a clear advantage in combining organoid culture with microsystems for drug development. The main objective of this review is to address the recent advances in organoids and microphysiological systems highlighting crucial technologies for reaching a synergistic strategy, including bioprinting.

The pathological condition of obesity is accompanied by a dysfunctional adipose tissue. We postulate that subcutaneous, preperitoneal and visceral obese abdominal white adipose tissue depots could have stromal vascular fractions (SVF) with distinct composition and adipose stem cells (ASC) that would differentially account for the pathogenesis of obesity. In order to evaluate the distribution of SVF subpopulations, samples of subcutaneous, preperitoneal and visceral adipose tissues from morbidly obese women (n = 12, BMI: 46.2±5.1 kg/m²) were collected during bariatric surgery, enzymatically digested and analyzed by flow cytometry (n = 12). ASC from all depots were evaluated for morphology, surface expression, ability to accumulate lipid after induction and cytokine secretion (n = 3). A high content of preadipocytes was found in the SVF of subcutaneous depot (p = 0.0178). ASC from the three depots had similar fibroblastoid morphology with a homogeneous expression of CD34, CD146, CD105, CD73 and CD90. ASC from the visceral depot secreted the highest levels of IL-6, MCP-1 and G-CSF (p = 0.0278). Interestingly, preperitoneal ASC under lipid accumulation stimulus showed the lowest levels of all the secreted cytokines, except for adiponectin that was enhanced (p = 0.0278). ASC from preperitoneal adipose tissue revealed the less pro-inflammatory properties, although it is an internal adipose depot. Conversely, ASC from visceral adipose tissue are the most pro-inflammatory. Therefore, ASC from subcutaneous, visceral and preperitoneal adipose depots could differentially contribute to the chronic inflammatory scenario of obesity.

Introduction: Subcutaneous adipose tissue is an interesting source of autologous stem cells with a fundamental role in the pathophysiology of obesity, metabolic syndromes and insulin resistance. We hypothesize that obesity could alter the stromal-vascular fraction (SVF) and adipose stem cell (ASCs) functions, which could compromise its regenerative behavior. Furthermore, we aimed to evaluate whether ASCs derived from post bariatric surgery ex-obese women maintain their functions in a similar fashion as do those from individuals who have never been obese. Methods: The SVF of subcutaneous adipose tissue from control (n = 6, body mass index – BMI - 27.5 ± 0.5 kg/m²), obese (n = 12, BMI 46.2 ± 5.1 kg/m²) and post bariatric surgery ex-obese (n = 7, initial BMI 47.8 ± 1.3 kg/m²; final BMI 28.1 ± 1.1 kg/m²) women were isolated and evaluated by flow cytometry. ASCs were tested for lipid accumulation by perilipin, adipose differentiation-related protein (ADRP) and Oil Red O staining after adipogenic stimulus. The cytokines secreted by the ASCs and after lipid accumulation induction were also evaluated. Results: The subcutaneous adipose tissue of obese and post bariatric surgery ex-obese women was enriched in pericytes (p = 0.0345). The number of supra-adventitial cells was not altered in the obese patients, but it was highly enriched in the post bariatric surgery ex-obese women (p = 0.0099). The ASCs of the post bariatric surgery ex-obese patients secreted more MCP-1 (monocyte chemoattractant protein-1; p = 0.0078). After lipid accumulation induction, the ASCs of the patients in all groups secreted less IL-6 than the ASCs with no adipogenic stimulus (p < 0.0001). Obese ASCs with lipid accumulation secreted the highest amount of IL-6 (p < 0.001) whereas the ASCs from the controls secreted the highest amount of adiponectin (p < 0.0001). The ASCs from the post bariatric surgery ex-obese patients showed the highest levels of lipid accumulation whereas those from the obese women had the lowest levels (p < 0.0001). Conclusions: SVF content and ASC behavior are altered in the subcutaneous adipose tissue of morbid obese women; these changes are not completely restored after bariatric surgery-induced weight loss. The cellular alterations described in this study could affect the regenerative effects of adipose stem cells. Further investigations are required to avoid jeopardizing the development of autologous stem cell-based therapies.

Top-down tissue engineering aims to produce functional tissues using biomaterials as scaffolds, thus providing cues for cell proliferation and differentiation. Conversely, the bottom-up approach aims to precondition cells to form modular tissues units (building-blocks) represented by spheroids. In spheroid culture, adult stem cells are responsible for their extracellular matrix synthesis, re-creating structures at the tissue level. Spheroids from adult stem cells can be considered as organoids, since stem cells recapitulate differentiation pathways and also represent a promising approach for identifying new molecular targets (biomarkers) for diagnosis and therapy. Currently, spheroids can be used for scaffold-free (developmental engineering) or scaffold-based approaches. The scaffold promotes better spatial organization of individual spheroids and provides a defined geometry for their 3D assembly in larger and complex tissues. Furthermore, spheroids exhibit potent angiogenic and vasculogenic capacity and serve as efficient vascularization units in porous scaffolds for bone tissue engineering. An automated combinatorial approach that integrates spheroids into scaffolds is starting to be investigated for macro-scale tissue biofabrication.