In Vivo Evaluation of Mechanically Processed Stromal Vascular Fraction in a Chamber Vascularized by an Arteriovenous Shunt.

Bong-Sung Kim,Nicole Lindenblatt,Epameinondas Gousopoulos,Huang-Kai Kao,Marco Guidi,Shih-Heng Chen,Mauro Vasella

doi:10.3390/pharmaceutics14020417

Bong-Sung Kim, Nicole Lindenblatt + Show 5 more

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https://doi.org/10.3390/pharmaceutics14020417

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Abstract

Mechanically processed stromal vascular fraction (mSVF) is a promising source for regenerative purposes. To study the in vivo fate of the mSVF, we herein used a vascularized tissue engineering chamber that insulates the target mSVF from the surrounding environment. In contrast to previous models, we propose an arteriovenous (AV) shunt between saphenous vessels in rats without a venous graft. Mechanical SVF was processed from the fat pads of male Sprague Dawley rats, mixed with a fibrin hydrogel and implanted into an inguinal tissue engineering chamber. An arteriovenous shunt was established between saphenous artery and vein. On the contralateral side, an mSVF-fibrin hydrogel mix without vascular axis served as a non-vascularized control. After two and six weeks, rats were sacrificed for further analysis. Mechanical SVF showed significant numbers of mesenchymal stromal cells. Vascularized mSVF explants gained weight over time. Perilipin and CD31 expression were significantly higher in the mSVF explants after six weeks while no difference in DAPI positive cells, collagen deposition and FABP4 expression was observed. Morphologically, no differentiated adipocytes but a dense cell-rich tissue with perilipin-positive cells was found after six weeks. The phosphorylation of ERK1/2 was significantly enhanced after six weeks while Akt activation remained unaltered. Finally, mSVF explants stably expressed and released VEGF, bFGF and TGFb. Vascularized mSVF is able to proliferate and express adipocyte-specific markers. The AV shunt model is a valuable refinement of currently existing AV loop models in the rat which contributes to the fundamental 3R principles of animal research.

Highlights

Introduction iationsAdipose tissue has advanced to one of the major tools in regenerative medicine including regenerative plastic surgery and tissue engineering
We found that the mRNA of all three growth factors were stably expressed in Mechanically processed stromal vascular fraction (mSVF) after two and six weeks (Figure 9D–F)
The length gain by a graft offers undeniable benefits, earlier studies have shown that the sprouting of new blood vessels primarily originates from the vein and artery in the early stages [17] and later on from the vein, artery and the graft [24]

Summary

Introduction

Adipose tissue has advanced to one of the major tools in regenerative medicine including regenerative plastic surgery and tissue engineering. The discovery of adiposederived stem cells, or rather, adipose-derived stromal cells (ASCs) [1], has had a incomparable impact as ASCs mediate effects comparable to those of other mesenchymal stem cells (MSCs), though with a much more acceptable donor site morbidity. ASCs have been examined for uncountable clinical applications such as wound healing, tissue augmentation, skin rejuvenation, neurological and gastrointestinal disease, cardiovascular disease, musculoskeletal diseases and many more [2,3]. ASCs appear to be a promising cell source for tissue engineering, e.g., by cultivating ASCs on scaffolds to replace, modify or augment desired tissue [4]. Despite the excitement generated over the years, methodological and regulatory issues have significantly hampered the clinical

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