Use of Adipose-Derived Mesenchymal Stem Cells to Increase Viability of Composite Grafts.

Objective: Chondrocutaneous composite grafts figure among the reconstruction alternatives for alar rim defects resulting from tumor resection and trauma. The major problem with composite grafts is the limited graft survival area. In the present study, the authors aimed to increase the survival area of composite grafts by utilizing the ability of stem cells to promote neovascularization which is crucial in composite graft viability.

Methods: The study included 36 adult Wistar Albino rats, which were allocated to 6 groups. Groups 1, 2, and 3 were the groups in which the grafts were implanted immediately after the defect was formed, and Groups 4, 5, and 6 were those in which grafts were adapted 4 days after the defect was formed. Composite grafts of 1 × 1 cm containing both the cartilage and the skin were prepared from 1 ear, and after forming punctures and incisions on the cartilage, the grafts were adapted to the 1 × 1 cm defects on the back. The backs of the rats in groups 1 and 4 were injected with adipose-derived stem cell (ADSC), those in groups 2 and 5 with medium solution, while the rats in Groups 3 and 6 did not receive any injection. The procedures were followed by histopathological and scintigraphic evaluations.

Results: An evaluation of the statistical results showed that composite graft survival areas of the group treated with stem cells increased significantly, in comparison with control and medium groups. When scintigraphic evaluations were considered, it was seen that the group treated with stem cells had significantly higher radioactive substance retention than the control group. Histopathological examination demonstrated that microscopic survival rates in the stem cell group were higher than those in the control group. Green fluorescent protein (GFP) was used in the experiment to tag adipose tissue-derived stem cells. Immunofluorescence staining studies showed less apoptosis and fewer GFP (+) stem cells in the composite grafts of the stem cell group. However, apoptosis was more severe in the control and medium groups which also had decreased vascularity in the graft.

Discussion: As the authors have shown in the present study, ADSCs have favorable effects on the viability of composite grafts. They have increased the survival rate of the grafts to a considerable extent. As a clinical implication of this experimental study, the authors think that in the patient of auricular and nasal defects involving the cartilage and the skin, injection of the ADSC and the adaptation of composite grafts 4 days after the preparation of the receiving bed may increase the composite graft viability rates. Thus, it has been found that if the composite grafts are implanted 4 days after stem cell injection, the injection of adipose tissue-derived mesenchymal stem cells is useful in enhancing the survival of composite grafts.