Safety and Efficacy of Autologous Melanocyte/Keratinocyte Transplantation in Patients with Refractory Stable Vitiligo.

BACKGROUND: Vitiligo is a common depigmentation skin disease associated with significant psychosocial morbidity and profound effect on the quality of life. The treatment of vitiligo is still a major challenge in the field of dermatology. Currently, topical steroids, calcineurin inhibitors, ultraviolet phototherapy, surgery, and cultured and non-cultured epidermal melanocyte transplantation are used for the treatment of vitiligo. However, the effectiveness of these treatment modalities is limited by the lack of response, long-term treatment periods, high cost, and inevitable adverse effects. OBJECTIVES: In this study, we aimed to evaluate the efficacy of intraepidermal injection of autologous non-cultured melanocytes and keratinocytes as an alternative therapy for the refractory and stable (RS) vitiligo. METHODS: The treatment procedure was performed on thirty-nine RS vitiligo patients. The autologous skin grafts obtained from the buttock area and epidermis were separated from dermis using dispase. Single-cell autologous melanocytes and keratinocytes were prepared from the epidermis by trypsin/ethylene diamine tetra acetic acid and injected at the concentration of 100-400 × 103 cells/cm2, intra-epidermally to the selected vitiligo lesions. Vitiligo re-pigmentation was monitored employing photography. Photographs were taken prior to and 2, 4, and 6 months after the cell transplantation. Improvement of the skin depigmentation was classified as follows: <25% as minimal response, 26-50% as moderate response, 51-75% as good response, and finally 76-100% as excellent response. RESULTS: Cell infusion appeared to be safe as none of the patients exhibited any adverse effects. At the end of the sixth month follow-up period, of the treated patients, 12.8% demonstrated an excellent response, 36% exhibited a good response, and 51.2% showed a moderate to minimal response to the administered therapy. Obtained significant p value for Wilcoxon test over the checkpoints at 2nd, 4th, and 6th month (p = 0.03, 0.04, and 0.039, respectively) post-cell transplantation confirmed notable growing trend in the re-pigmentation. CONCLUSION: Our findings provide a strong support for the therapeutic efficacy of autologous non-cultured melanocytes and keratinocytes in patients with RS vitiligo.

Mathematical modeling of tumor-induced immunosuppression by myeloid-derived suppressor cells: Implications for therapeutic targeting strategies.

Myeloid-derived suppressor cells (MDSCs) belong to immature myeloid cells that are generated and accumulated during the tumor development. MDSCs strongly suppress the anti-tumor immunity and provide conditions for tumor progression and metastasis. In this study, we present a mathematical model based on ordinary differential equations (ODE) to describe tumor-induced immunosuppression caused by MDSCs. The model consists of four equations and incorporates tumor cells, cytotoxic T cells (CTLs), natural killer (NK) cells and MDSCs. We also provide simulation models that evaluate or predict the effects of anti-MDSC drugs (e.g., l-arginine and 5-Fluorouracil (5-FU)) on the tumor growth and the restoration of anti-tumor immunity. The simulated results obtained using our model were in good agreement with the corresponding experimental findings on the expansion of splenic MDSCs, immunosuppressive effects of these cells at the tumor site and effectiveness of l-arginine and 5-FU on the re-establishment of antitumor immunity. Regarding this latter issue, our predictive simulation results demonstrated that intermittent therapy with low-dose 5-FU alone could eradicate the tumors irrespective of their origins and types. Furthermore, at the time of tumor eradication, the number of CTLs prevailed over that of cancer cells and the number of splenic MDSCs returned to the normal levels. Finally, our predictive simulation results also showed that the addition of l-arginine supplementation to the intermittent 5-FU therapy reduced the time of the tumor eradication and the number of iterations for 5-FU treatment. Thus, the present mathematical model provides important implications for designing new therapeutic strategies that aim to restore antitumor immunity by targeting MDSCs.

Myeloablative and immunosuppressive properties of treosulfan in mice.

OBJECTIVE: Treosulfan is a prodrug with a specific clinical activity in ovarian carcinoma and other solid tumors. Due to its myeloablative and immunosuppressive effects, its use in conditioning regimens prior to allogeneic stem cell treatment (SCT) has been proposed. In the present preclinical study, myeloablative as well as immunosuppressive properties of treosulfan were compared with those of busulfan and cyclophosphamide. METHODS: Three groups of BALB/c mice were treated with treosulfan, cyclophosphamide, or busulfan at sublethal doses that maintained survival without bone marrow support. The control group was left untreated. At different intervals, colony-forming unit granulocyte macrophage assay was performed on marrow cells. Additionally, immunological analyses were performed using spleen cells. RESULTS: We found that treosulfan and busulfan induced a high and persisting degree of myeloablation, as compared with cyclophosphamide. Moreover, treosulfan was more effective in depletion of splenic B and T cells in comparison with busulfan and cyclophosphamide. Furthermore, T cells isolated from the spleens of treosulfan- or busulfan-treated mice were not responsive to allogeneic cells compared with that observed in controls and cyclophosphamide-treated mice. Treatment with treosulfan induced only interleukin-2 production in spleen cells for a short time and had no significant effect on synthesis of tumor necrosis factor-alpha and/or interferon-gamma as compared with that observed in splenic T cells isolated from mice treated with either busulfan or cyclophosphamide. CONCLUSION: Our findings suggest that treosulfan possesses both myeloablative and immunosuppressive properties and may be used as a single agent for conditioning prior to bone marrow transplantation.