Role of Mesenchymal Stem Cells in Fat Grafting

Overview

Contour deformity of face causes both functional as well as aesthetic problems for the patient. Fat being an autologous tissue source is considered as an ideal soft-tissue filler because it is abundant, readily available, inexpensive, host compatible, and can be harvested easily and repeatedly. However absorption of grafted fat is a major problem resulting in lack of consistency of final clinical outcome. Adipose tissue derived mesenchymal stem cells have the potential to enhance the viability of the grafted fat and the reliability of the final outcome of surgery. In the current study potential of mesenchymal stem cells will be studied by comparing two groups of patients requiring fat grafting for contour deformities of face. Control group will have fat graft with out enrichment with stem cells whereas experimental group will have their fat graft enriched with mesenchymal stem cells. Comparison will be made regarding viability of grafted fat in two groups.

Contour deformities of the face requiring soft tissue augmentation often result from conditions such as congenital disorders, acquired diseases, and traumatic and developmental deformities. Significant contour deformity of face causes both functional as well as aesthetic problems for the patient. Conventionally, these problems are treated by allogenic fillers, major flap surgery and fat grafting.1 However; different problems are associated with above mentioned treatment options. For example, allogenic fillers are foreign material that poses not only allergic reactions but also rapid absorption at the site of application. Similarly, flap surgery, in the form of pedicled and free flaps, produces considerable donor site morbidity. In addition, fine- tuning is impossible with flap, and tissue transferred in the form of flap may act as blob. Autologous fat grafting has gained pervasive acceptance for the management of contour deformities of the face. Fat being an autologous tissue source is considered as an ideal soft-tissue filler because it is abundant, readily available, inexpensive, host compatible, and can be harvested easily and repeatedly.2 Although the practice of fat grafting is not new and it is a safe and natural method of soft-tissue augmentation, the viability and reliability of transplanted fat grafts remains poorly studied. One major concern is the lack of consistency of final clinical outcome, which often requires multiple fat grafting procedures making it expensive. Rate of fat absorption may reach up to 40% to 80%.However, previously published data have failed to produce a cohesive algorithm of the required components for successful, consistent and durable fat transplantation.3 In order to overcome problems associated with fat grafting, other innovative techniques are required. The role of fat auto-transplantation in plastic surgery has evolved from a controversial technique designed for simple volume augmentation to the foundation for the innovative and burgeoning field of regenerative medicine. This is based on the fact that adipose tissue contains adipocytes and the stromal vascular fraction (SVF) consisting of multiple cell types such as circulating blood cells, fibroblasts, pericytes, endothelial cells, and mesenchymal stem cells (MSCs). Adipocytes account for 20 percent or fewer of the total number of cells in adipose tissue4whereasthere are only 3% MSCs in SVF of adipose tissue.5 Although this percentage is relatively low, this cell type is the main contributor in overall healing process. MSCs derived from adipose tissue (AT-MSCs) have high proliferative potential and ability to differentiate into mesenchymal (adipose, bone, cartilage) and non-mesenchymal (neuron like cells) lineages.6,7,8 AT-MSCs have been shown to enhance angiogenesis, decrease apoptosis and modify the local inflammatory response owing to their immunosuppressive and immunomodulatory properties.9 Therefore, the current study is designed to evaluate the effect of fat grafting and AT-MSCs together on contour deformities of face. By combining traditional fat graft with AT-MSCs, tissue viability and therefore the consistency of graft survival may be improved. In the current model investigators propose that transferred fat may act as a natural scaffold and temporary filler to restore the volume immediately while AT-MSCs will start participating in multiple parameters of tissue regeneration. This model supports the "host replacement theory" that has been put forward to describe how fat grafts survive after they are transplanted.10 Due to problems associated with fat grafting alone, it is desirable to solve such issues by using innovating techniques. In the current study investigators propose the novel idea of enrichment of conventional fat graft with ex-vivo expanded AT-MSCs to enhance the viability of the grafted fat and the reliability of the final outcome of surgery. Recent animal studies have suggested that AT-MSCs that have been expanded before administration could help preserve grafted fat and improve outcomes.11 Thus rationale of current study is to compare the outcome of conventional fat grafting with stem cell enriched fat grafting for contour deformities of face. If enrichment of fat graft with AT-MSCs can decrease its absorption rate, this innovative strategy can make fat transfer a reliable option for soft tissue augmentation. This can definitely improve final clinical outcome at lesser cost and reduced donor site morbidity