Critical skin wounds are a major cost for the health sector and lead to immense suffering for the patients. One way to facilitate healing of these wounds is through autologous autologous adipose tissue transplants. However, the implanted tissue needs to be vascularized or it will suffer from necrosis. To combat this Stromal vascular fraction (SVF), which is isolated from fat, can be utilized as it has been shown to promote both vascularization and the wound healing process. In this project we evaluate a method which combines SVF with 3D Bioprinting to create thick fat grafts for in situ vascularization.

METHODS:

Adipose tissue was taken with consent from patients undergoing plastic surgery and was isolated with MiniStem, device from JoinTechLabs, USA. Two MiniStem protocols were run: (i) lipoaspirate was fractured toward macerated fat graft and (ii) lipoaspirate was enzymatically treated in order of SVF harvest. Collected SVF was analyzed with FACS. Both fractions were mixed with a hydrogel composed of a mix of nanocellulose and alginate. The resulting cell laden hydrogels (bioinks) were 3D Bioprinted as gridded constructs with CELLINKs INKREDIBLE+ bioprinter. The properties of the final constructs and bioinks were evaluated from a rheological perspective using a rheometer and O-prints, a method developed in house. 

RESULTS: The o-print showed that the mixed hydrogels were homogenous and easily printable. Rheology testing revealed that the crosslinked bioink also displayed properties like that of the extracellular matrix. FACS of the extracted SVF fractions showed the presence of heterogeneous cell population with substantial presence of ASCs, pericytes, endothelial progenitors.

FACS data for SVF  isolated with Ministem

DISCUSSION & CONCLUSIONS: We have shown that we can isolate both fat and SVF from the same liposuction procedure.  These results also show that fat and SVF isolated with the MiniStem and mixed with biopolymers contains relevant cells and possesses good printability. High  expression of angiogenic markers in both protocols strongly indicates on potential angiogenic capacity.