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

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.

Methacrylated Gelatin as a Scaffold for Mechanically Isolated Stromal Vascular Fraction for Cutaneous Wound Repair

“…While the scaffold itself was designed for another research rationale, i.e., osteoarthritis and the design of a 3D structure by a custom bioreactor, our experiments neglected 3D characteristics as they are of secondary interest for wound healing purposes where the key goal is to generate a vascularized tissue layer. However, in accordance with O'Donnell's observations, our previous studies showed that mSVF has proadipogenic and importantly pro-angiogenic properties [27] that support mSVF as a suitable cell source. O'Donnell and colleagues used the same stock solution of GelMA (15 wt%), while photoactivation was only two minutes compared to five minutes in our approach, most likely due to smaller construct sizes and the more liquid texture of mSVF.…”

“…Also, the authors used a composite hydrogel composed of GelMA and hyaluronan. We, by contrast, intentionally skipped additional components, as the mSVF itself is not a pure cell mixture but also includes significant amounts of extracellular matrix (ECM) molecules as demonstrated earlier [ 27 ]. O’Donnell et al investigated GelMA as a promising scaffold in an in vitro study reporting increased cell differentiation of ASCs into mature adipocytes when combined with the hydrogel [ 28 ].…”

“…Although not specifically investigated, we hypothesize that GelMA made the increase of the previously mentioned factors possible and likely enhances cell migration as well. More recently, we provided the first evidence for in vivo adipogenesis of mSVF and fibrin hydrogel in an advanced supermicrosurgical rat model [ 27 ]. DAPI/phalloidin staining revealed a visual increase in cell nuclei, actin filaments, cell elongation, and alignment, further indicating that GelMA may provide a conducive microenvironment that incorporates extracellular matrix components of mSVF.…”

Comparison of the Effectiveness of Methods for Obtaining and Application the Stromal-Vascular Fraction of Adipose Tissue in an Experimental Model of a Donor Wound in Burns

“…Luer lock) Nano Transfer PB-600.75 (ООО «ПАКТ-МедСервис», Россия) минимум 30 пассажами. Эмульсифицированный жир центрифугировали при 1 200 g в течение 5 мин., в результате чего образовавшийся верхний слой убирали, нижний слой использовали в качестве мСВФ [16].…”