Vascularization of Microvascular Fragment Isolates from Visceral and Subcutaneous Adipose Tissue of Mice

Abstract

Background: Adipose tissue-derived microvascular fragments (MVF) represent effective vascularization units for tissue engineering. Most experimental studies in rodents exclusively use epididymal adipose tissue as a visceral fat source for MVF isolation. However, in future clinical practice, MVF may be rather isolated from liposuctioned subcutaneous fat tissue of patients. Therefore, we herein compared the vascularization characteristics of MVF isolates from visceral and subcutaneous fat tissue of murine origin. Methods: MVF isolates were generated from visceral and subcutaneous fat tissue of donor mice using two different enzymatic procedures. For in vivo analyses, the MVF isolates were seeded onto collagen-glycosaminoglycan scaffolds and implanted into full-thickness skin defects within dorsal skinfold chambers of recipient mice. Results: By means of the two isolation procedures, we isolated a higher number of MVF from visceral fat tissue when compared to subcutaneous fat tissue, while their length distribution, viability and cellular composition were comparable in both groups. Intravital fluorescence microscopy as well as histological and immunohistochemical analyses revealed a significantly reduced vascularization of implanted scaffolds seeded with subcutaneous MVF isolates when compared to implants seeded with visceral MVF isolates. Light and scanning electron microscopy showed that this was due to high amounts of undigested connective tissue within the subcutaneous MVF isolates, which clogged the scaffold pores and prevented the interconnection of individual MVF into new microvascular networks. Conclusion: These findings indicate the need for improved protocols to generate connective tissue-free MVF isolates from subcutaneous fat tissue for future translational studies.

PM2.5, component cause of severe metabolically abnormal obesity: An in silico, observational and analytical study

“…In mice, epididymal adipose tissue is representative of visceral adipose tissue [ 67 ], and as known, this adipose tissue differs from subcutaneous adipose tissue [ 68 ]: i. Subcutaneous adipose tissue presents a heterogeneous mixture of mature unilocular adipocytes interspersed with small multilocular adipocytes of significantly reduced diameter, providing a higher density of adipocytes in this tissue compared to visceral adipose tissue [ 67 ]. ii.…”

Bioprinted dermis with human adipose tissue‐derived microvascular fragments promotes wound healing

“…The digestion of collagenase during the separation of MVFs derived from adipose tissue in mice or rats should be limited to a maximum of 10 min (Später et al, 2020), because prolonged digestion causes the microvascular fraction to decompose into the stromal vascular fraction (SVF) (Bensemmane et al, 2021). However, the subcutaneous fat has a high density of fat cells and is characterized by abundant elastic collagen fibers (Später et al, 2022). Our study also obtained similar results: a large number of elastic and collagen fibers surrounded the blood vessels and could not be completely degraded.…”

“…We obtained similar results with vascular fragments that could reform the microvascular network on Day 9, which was markedly shorter than that on Day 14, as required for normal umbilical vein endothelial cells to form blood vessels (Ben‐Shaul et al, 2019). These vascular segments exhibit an intact microvascular morphology, including stable lumen, endothelial cells, and perivascular encapsulated cells, and most MVFs exhibit stable α‐smooth muscle actin‐positive cells after isolation (Frueh, Menger, et al, 2017; Später et al, 2022). From our results, stable cells were encapsulated with perivascular SMA‐positive around CD31‐positive vessels; therefore, we speculated that this part represented the original MVF that we isolated, whereas the SMA portions stemmed from MVFs.…”

Engineering Functional Vascularized Beige Adipose Tissue from Microvascular Fragments of Models of Healthy and Type II Diabetes Conditions

“…The ease by which subcutaneous adipose tissue can be isolated using minimally invasive procedures allows for the potential to translate into applications using autologous subcutaneous adipose tissues. 44,45 Future work in understanding metabolic dysfunction should explore whether MVF deriving from diabetic subjects exhibit differences between adipose depots 79 or gender. 80 Moreover, characterization of MVF deriving from other diseased/metabolically altered states should also be characterized, and techniques developed to maximize their adipose and vascular development and function.…”