Evaluating the Efficacy of the Melanocyte Keratinocyte Transplantation Procedure in the Treatment of Vitiligo

Overview

Vitiligo is a dermatologic disease characterized by depigmentation of the skin. While the loss of melanocytes observed in vitiligo is driven by the immune system, repigmentation of the skin that occurs during UV light treatment is driven by melanocytes that migrate out of the hair follicle and into the epidermis or the activation of stem cells within the epidermis. Unfortunately, some skin areas affected by vitiligo have very few hair follicle melanocytes and an indeterminate number of epidermal melanocytes and therefore unable to respond to light therapy. This pilot study seeks to examine the relative efficacy of different harvesting methods for the melanocyte keratinocyte transplant procedure (MKTP) in the treatment of vitiligo. In addition, this study will analyze the tissue of excess tissue harvested during the procedure to identify distinct cellular and molecular features of chronic vitiligo. Patients in Dr. Ganesan's clinic at the UCI (University of California, Irvine) Department of Dermatology will be approached for participation in the study. The study will include both men and women and will not be limited by race or ethnicity. The investigators will exclude individuals less than 18 years old for the study as the investigators believe it would be difficult for these subjects to tolerate the melanocyte keratinocyte transplant procedure. Participants will be offered a melanocyte keratinocyte transplant procedure with one of the three different tissue harvesting methods (a blade, suction blister) and the method without dissociation (Cellutome). This study has three arms: 1. MKTP with Surgical Blade 2. MKTP with Negative Pressure Instrument (suction blistering device). 3. Suction blister grafting without cell dissociation utilizing Cellutome (a device used for treating chronic burn wounds)

In the first arm of the study, a normally pigmented area on the patient was anesthetized with 1% lidocaine with epinephrine. Using a surgical knife, the investigator removed a small portion of the epidermis that is unaffected by vitiligo from a small area (2cm2) on the patient's thigh to obtain donor cells. Epidermis that was harvested with the surgical knife was washed with Lactated Ringer's solution three times and then dissociated using trypsin to separate the cells into a single cell suspension. The recipient area to be grafted was ablated with an Erbium YAG(yttrium aluminum garnet)laser. Half of the dissociated single cells from the donor area (thigh)was then transplanted on to the area affected by vitiligo that the participant is interested in grafting (5 cm2 area). The investigator then evaluated response to treatment in the transplanted areas at 1 day, 1 week, 1 month and 3 months, and 6 months by both photography and quantifying the VASI(Vitiligo Area Scoring Index) score. VASI(Vitiligo Area Scoring Index)is the percentage of vitiligo involvement and is calculated in terms of hand units. One hand unit is approximately equivalent to 1% of the total body surface area. In the second arm of the study, the investigator used a minimally invasive procedure (suction blister grafting) to sample the grafted skin and donor skin- this method can separate the epidermis from the dermis without inducing a scar. A normally pigmented area on the upper thigh was anesthetized with 1% lidocaine with epinephrine. Using a suction blister technique, the investigator removed a small portion of the epidermis that was unaffected by vitiligo from a small area (4 cm2 or 0.6 inch cm2) on the patient's thigh to obtain donor cells. Epidermis that was harvested was washed with Lactated Ringer's solution three times and then dissociated using trypsin to separate the cells into a single cell suspension. The recipient areas to be grafted were used to harvest epidermis using a suction blister device. Half of the dissociated single cells from the donor area (thigh) were then transplanted on to the area affected by vitiligo that the patient was interested in grafting (5 cm2 area or 0.7 inch2). The suction blister skin from the recipient sites was simultaneously dissociated into a single cell suspension. A portion of the remainder of the cells (from both the donor and recipient site) was subjected to flow sorting to quantify the populations of melanocytes and keratinocytes and to detailed molecular analysis (single-cell RNA sequencing and histology) to characterize the molecular features of chronic vitiligo. The investigator then evaluated response to treatment in the transplanted areas at 1 day, 1 week, 1 month and 3 months, and 6 months by both photography and quantifying the VASI score. This arm of the study is complete. In the third arm of the study, the investigator uses a minimally invasive procedure (suction blister grafting without cell dissociation) to sample the grafted skin and donor skin- this method can separate the epidermis from the dermis without inducing a scar. A normally pigmented area on the upper thigh will be anesthetized with 1% lidocaine with epinephrine. Using an epidermal harvesting system which is a suction blister technique, the investigator will remove multiple small portions (about 128 blisters-1.8 mm in diameter) of the epidermis unaffected by vitiligo from a small normal area (5 cm2 ) on the patient's thigh to obtain donor cells and using a regular negative pressure instrument for removing four samples for histopathological study (two from the vitiligo area and two from the normal donor skin). The epidermis from the donor area (thigh) will then be transplanted on to the area affected by vitiligo that the patient is interested in grafting. Also, the four portions from the normal skin and the recipient site will be sent for the histopathological evaluation. The investigator will then evaluate response to treatment in the transplanted areas at 1 day, 1 week, 1 month and 3 months, and 6 months by both photography, quantifying the change in depigmented surface area, and the VASI(Vitiligo Area Scoring Index) score. Also, the investigator will evaluate the two vitiligo samples and two normal skin samples through histopathology to assess where the unique populations of cells identified in their RNA-sequencing analysis are localized (obtained from arm 2). The investigator hypothesizes that his transplant procedure will yield excellent to good repigmentation, resulting in a mean of 60% reduction in surface area (SD=30%) from baseline to 6-month follow up. With a sample size of 5 patients, this study will achieve 90% power to test this hypothesis based on a two-sided paired t-test at p=0.05 significance level. In addition, the investigator will compare the results from the 7 patients harvested using the surgical blade technique (procedure already completed and follow up results pending) with the results from 7 patients harvested with the suction blisters (completed) and seven patients from the newly proposed experimental group (three completed to date).