A comparative study of efficacy of split-thickness skin grafting versus autologous melanocyte transfer in the management of stable vitiligo

Abstract

Background

Vitiligo is a depigmenting skin disorder resulting from the loss of melanocytes in the epidermis. Surgical treatment is indicated in resistant stable vitiligo that does not show adequate response to medical therapy. This study aims at comparing the efficacy of repigmentation by split-thickness skin grafting (STSG) versus autologous non-cultured melanocyte transfer (AMT) in the management of stable vitiligo.

Methods

A total of 22 patients were recruited, which included 100 stable vitiligo patches. Fifty patches were subjected to STSG, and the remaining 50 were subjected to AMT. The patients were followed up at monthly intervals for six months to assess the degree of repigmentation.

Results

The results at the end of six months were as follows: 40% patches in group A and 42.5% in group B exhibited >75% repigmentation. The outcome was better over the limbs, acral parts and joints. The average donor-to-recipient area ratio for group A was 1:1, whereas that for group B was 1:3.2.

Conclusion

Both STSG and AMT are effective surgical modalities in the management of stable vitiligo. However, AMT has cosmetically better good outcomes, requires a smaller size of the donor area and has minimal complications over both recipient and donor areas.

Introduction

Vitiligo is a pigmentary disease of skin and mucous membranes, characterised by depigmented macules resulting from the absence of or reduction in melanocytes. The disease causes cosmetic disfigurement, leading to social and psychological impacts in affected individuals. Choice of treatment is based on minimising disease activity and inducing pigmentation. Many a time, merely medical therapy, in the form of topical and systemic steroids and immunomodulators, may not produce the desired results. The depigmented macules may remain stable without any change in size or colour. Such patches having stability for more than one year are suitable for treatment by surgical methods.

Surgical therapy is based on autologous transplant of melanocytes or the melanocyte-bearing epidermis. This can be performed by a wide variety of methods. These include both tissue grafting techniques such as mini punch grafting,¹ suction blister epidermal grafting² and thin split-thickness grafting³ as well as cellular grafting techniques such as non-cultured melanocyte transfer⁶ and cultured melanocyte transplantation. Tissue grafting techniques are established and are time-tested modalities, whereas the cellular grafting techniques are relatively novel modalities. This study was undertaken to compare two surgical modalities in the management of stable vitiligo: one being a tissue grafting technique (split-thickness grafting) and the other being a cellular grafting technique (non-cultured melanocyte transfer).

Materials and methods

The study was designed as a prospective, single-centre study. Institutional Ethics Committee clearance was taken before starting the study. Informed consent was taken from all patients. Individuals of both sexes, in the age group 16–60 years and having stable lesions of vitiligo (no increase in size of existing lesions or no new lesions appearing in the past one year) were included in the study. Individuals with active/progressive vitiligo, with any chronic ailment/medication, on immunosuppressant therapy or having keloidal tendencies or infections were excluded from the study.

The simple random sampling method was used for sample selection. Sample size determination was carried out using the following values: (1-α) = 0.98, (1-β) = 0.80, π1 = 0.48, π2 = 0.21. The total sample size calculated was 98. Therefore, 100 stable sites (in 22 patients) were enrolled for surgery by either of the modalities. After obtaining informed consent, the patients were subjected to a detailed clinical examination including a thorough dermatological examination and a set of investigations.

The patients were distributed by the simple randomisation method (by flipping of coin) into group A and group B of 50 sites each. Two modalities of vitiligo surgery were used. Group A (consisting of 18 sites on the arms and legs, 12 sites on the hands and feet, 10 sites on the joints, 5 sites on the face and neck, 3 sites on the trunk and 2 sites on the flexures) was subjected to split-thickness skin grafting (STSG),^3,4 and group B (consisting of 16 sites on the arms and legs, 11 sites on the hands and feet, 9 sites on the joints, 6 sites on the face and neck, 5 sites on the trunk and 3 sites on the flexures) was subjected to autologous non-cultured melanocyte transfer (AMT).^5,6

The donor graft was harvested from the anterolateral aspect of the thigh for both the procedures. After surgical cleaning and infiltration of local anaesthesia, graft harvesting was performed using a manual dermatome (SOBER Hand dermatome; manufactured by Humeca, The Netherlands). In case of STSG, the harvested graft was directly applied over the dermabraded recipient area. The grafted area was then covered with paraffin gauze and thereafter secured with gauze pieces and pressure dressings.

In case of AMT, the harvested grafts were immersed in trypsin Ethylene Diamine Tetra Acetic acid (EDTA) and then placed in an incubator at 37 °C for 50 min. Thereafter, the trypsin inhibitor was added to neutralise the action of trypsin EDTA. This was followed by separation of the epidermis from the dermis. The dermal pieces were discarded, and epidermal pieces were placed in Dulbecco's Modified Eagle's Medium/F12 (DMEM). The epidermal sheet was gently teased with a forceps to separate the melanocytes that fell into the medium. DMEM solution containing these melanocytes was subjected to centrifugation at 2000 rpm for 10 min. The supernatant fluid was discarded, and the melanocyte cell pellet was suspended in 1 ml of DMEM to obtain a uniform cell suspension. This suspension was applied on the dermabraded recipient area and spread uniformly, followed by dressing with collagen sheet, sterile gauze pieces dipped in DMEM, transparent film dressing, dry gauze pieces and secured with micropore and elastoplast.

The transplanted part was immobilised, and the patient was placed on antibiotics (tablet: 500 mg of cefuroxime BD) and analgesics (tablet: 500 mg of paracetamol and 400 mg of Brufen BD) for 5 days. The donor area dressing was changed on alternate days. All dressings of donor and recipient sites were taken off completely after one week, after which the recipient sites were exposed to sun on alternate days.

Assessment methodology

The patients in both the groups were followed up at monthly intervals for six months. Objective assessment of repigmentation was performed by non-blinded observers; however, photographic evidence with standard aperture and lighting was used for recording the results. Grading of repigmentation was carried out based on the percentage of the area of repigmentation: <25%, poor; 26–50%, good; 51–75%, very good and ≥75%, excellent.

Analysis was performed for the onset, type and degree of repigmentation. The results were statistically analysed using the ‘chi-square test’ and ‘statistical significance’ (p-value) methods.

Results

A total of 22 patients were enrolled in the study, which included 50 vitiligo sites for STSG (group A) and 50 sites for AMT (group B). Ten sites each of both the groups (2 patients each) were not available for final data analysis as they were lost to follow-up.

In both group A and B, the maximum number of patients belonged to the age group of 16–25 years. Females outnumbered male patients in both group A and B. Focal and segmental types of lesions were considered for the study. The focal variety was more common than the segmental type, and the number of lesions seen on the extremities was more than that seen on the flexures in both the groups.

Group B showed an earlier onset of pigmentation, with 65% of the patches starting to repigment by 10–14 days after the procedure, and all the patches started to repigment by the end of the first month. The onset of pigmentation was later in group A (between 15 days and 1 month after the procedure). All three types of repigmentation—diffuse, perifollicular and marginal—were observed in the study. Group A showed the diffuse type of repigmentation in the maximum number of patches (85%), whereas the perifollicular type of repigmentation was more seen in group B.

Extent of repigmentation was calculated by assessing the percentage of the area that has repigmented. On objective assessment, repigmentation was <25% in both the groups for the maximum number of patches in the first month. Subsequently, the repigmentation area increased over the next six months in both the groups. At the end of six months, 40% of group A and 42.5% of group B patches exhibited >75% pigmentation (Fig. 1).

Fig. 1.

Chart showing comparison of the degree of repigmentation (objective assessment) at the end of 6 months for group A (STSG) and group B (AMT). STSG = split-thickness skin grafting; AMT = autologous non-cultured melanocyte transfer.

By using the chi-square test, the ‘p-value’ for the degree of repigmentation noted after 6 months was >0.05 (Table 1); therefore, there was no statistical association between treatment methodology and repigmentation. Thus, the final outcome, i.e., repigmentation, is independent of the modality of treatment. However, more patches in group B showed 50–75% and >75% pigmentation than in group A.

Table 1.

Comparison of degree of repigmentation (objective assessment) at the end of 6 months for group A (STSG) and group B (AMT).

Percentage of pigmentation	Group A		Group B		χ2 value	‘p’ value
	(N = 40)		(N = 40)
	n	%	n	%
<25%	4	10.00%	4	10.00%	2.22816	0.5264
25–50%	11	27.50%	6	15.00%
51–75%	9	22.50%	13	32.50%
>75%	16	40.00%	17	42.50%

STSG = split-thickness skin grafting; AMT = autologous non-cultured melanocyte transfer.

In group B, 75–100% repigmentation was seen in 83% of patches, with 5–10 years of stability, and in 100% of the patches, with 2–5 years of stability. However, in group A, more number of patches with 1–2 years and 2–5 years of stability were found to have a higher degree of repigmentation.

In group A, patches with the focal type of vitiligo showed higher degree of repigmentation than the segmental type, whereas in group B, patches with the segmental type demonstrated a higher degree of repigmentation. By both the methods, patches over the limbs, acral parts and joints demonstrated good repigmentation; however, better results were obtained in group B (Fig. 2(a and b), 3(a and b)). Flexural patches had poor results in both the groups. It was also observed that the patches having a smaller area showed better repigmentation, than patches with a larger area in both group A and B.

Fig. 2.

(a) Vitiligo over the fingers: before the procedure. (b) Vitiligo over the fingers after split-thickness skin grafting: 6 months after the procedure.

Fig. 3.

(a) Vitiligo over the knee: before the procedure. (b) Vitiligo over the knee after autologous non-cultured melanocyte transfer: 6 months after the procedure.

A total of 19 sites (23.75%) of the 80 operated sites achieved 100% repigmentation (9 of 40 sites in group A and 10 of 40 sites in group B). These patches were located on the limbs and acral parts. In group B, two lesions over the joints also achieved 100% repigmentation. No single patient with multiple patches achieved 100% repigmentation of all the grafted sites by either of the methods. Overall, 45% of segmental vitiligo sites and 21.6% of focal sites achieved 100% repigmentation. Hence, segmental patches showed overall better response in terms of complete repigmentation. A total of 5 patches, 3 (7.50%) in group A and 2 (5.0%) in group B, showed nil pigmentation at the end of six months. This was mostly observed with flexural patches. No single patient had failure of repigmentation of all the transplanted sites in both the groups.

In group A, the donor area is equal to the total recipient area, the donor-to-recipient area ratio being 1:1 (Table 2). In group B, the donor area is smaller than the cumulative recipient area, the average donor-to-recipient area ratio being 0.31 (1:3.2), i.e., 1 cm² of normal skin was sufficient to cover about 3.2 cm² of vitiliginous skin (Table 3). The largest cumulative recipient area transplanted in a single treatment session was 160 cm² in the present study.

Table 2.

Donor area vs recipient area size: group A.

Patient	Total recipient area (cm2)	Total donor area (cm2)	Donor-to-recipient ratio
1	12	12	1:1
2	4	4
3	20.6	21
4	6	6
5	59.5	60
6	25	25
7	40	40
8	24	24
9	33	33
10	15	15
11	15	15

Table 3.

Donor area-to-recipient area ratio: group B.

Patient	Total recipient area (cm2)	Total donor area (cm2)	Donor-to-recipient ratio
1	34.5	10.5	0.3 (1:3.3)
2	100	33	0.33 (1:3.0)
3	8.5	3	0.35 (1:2.9)
4	32	9	0.28 (1:3.6)
5	41.5	12	0.29 (1:3.4)
6	159.5	31.5	0.19 (1:5.3)
7	11.25	5	0.44 (1:2.3)
Average = 1:3.2

Colour mismatch, milia, infection and perigraft halo were the common complications observed on recipient sites in group A in this study, whereas only colour mismatch over few patches was seen in case of group B. Hyperpigmentation of the donor site was a common adverse effect in both the methods. Scarring was seen over two patches in group A, and koebnerisation leading to depigmentation was seen on one donor site each in both the groups.

Discussion

Vitiligo is characterised by lack of melanocytes, which are destroyed by various unidentified mechanisms. Surgical treatment is indicated in case of resistant stable vitiligo showing inadequate response to medical therapy. The various surgical modalities available are tissue grafting techniques such as split-thickness grafts, punch grafts and suction blister grafts and cellular grafting techniques such as autologous non-cultured epidermal cell suspensions and cultured melanocyte suspensions. The choice of surgical treatment depends on the type of vitiligo, extent and site of lesions, availability of equipment and expertise.

The present study compared the efficacy of STSG versus AMT in the management of 100 patches of stable vitiligo.

The statistical analysis revealed no significant association between the treatment methodology and degree of repigmentation. However, a cosmetically better outcome with uniform pigmentation and better colour and textural matching was seen in the AMT group than in the STSG group. Very few studies have been carried out in the past to compare these two modalities. In a long-term follow-up study by Olsson et al.⁷ better outcome in terms of degree of repigmentation was obtained by ultrathin epidermal sheet grafting than by basal layer suspension and cultured melanocytes. Sobhy et al.⁸ did a comparison between transplantation of non-cultured melanocytes and thin STSG and concluded that transplantation of melanocyte suspension gave better results and rapid response. However, this study recruited only 10 patients in each group, and the results were not statistically analysed. A randomised comparative study of STSG and AMT from India by Talukdar et al.⁹ found no statistically significant difference in repigmentation between the two procedures, but this study too was carried out on a smaller sample size of 25 sites each.

Few other studies assessed the efficacy of STSG and AMT individually. Table 4 summarises the results of the present study in comparison with other studies. The relatively better repigmentation obtained in the other studies than in the present study (specifically in the AMT group) may be attributed to the larger number of segmental lesions, administration of postoperative phototherapy and retreatment of lesions performed in the other studies.

Table 4.

Comparison of the degree of pigmentation in the present study with that in similar other studies.

S. No.	Name and year of the study	Sample size	Surgery	Study duration (years)	Response			Remarks
					Repigmentation	STSG	AMT
1	Present study	50 + 50	STSG and AMT	1.5	<25%	10.0%	10.0%	–
					25–50%	27.5%	15.0%
					50–75%	22.5%	32.5%
					>75%	40.0%	42.5%
2	Olsson and Juhlin7	40 + 52	STSG and AMT	7	<20%	37.5%	38.5%	Results were comparable in the STSG group, whereas results were better in the present study for the AMT group.
					20–65%	5.0%	21.0%
					65–95%	15.0%	19.0%
					>95%	42.5%	21.0%
3	Sobhy N et al8	10 + 10	STSG and AMT	1.5	<25%	20%	–	AMT showed results similar to our study. In case of STSG, results were better in the present study.
					25–50%	20%	–
					50–75%	40%
					>75%	20%	70.0%
4	Talukdar and Mitra9	25 + 25	STSG and AMT	1	<30%	28%	16%	Relatively better results in both the groups than in present study probably due to the use of postprocedural phototherapy.
					30–70%	20%	20%
					>70%	52%	64%
5	Majid and Imran10	84	STSG	1	>90%	83.0%	–	Better results than those obtained in the present study, could be due to the use of ultrathin grafts.
6	Mulekar et al11	142	AMT	6	<25%	–	24.0%	A larger number of patches showed almost complete pigmentation. Repeat procedures were performed in 23 patches.
					25–65%		9.0%
					65–95%		11.0%
					>95%		56.0%
7	Paul12	58	AMT	2	<30%	–	8.0%	Better pigmentation than that observed in the present study, could be due to the use of phototherapy to enhance pigmentation.
					30–70%		8.05
					70–90%		18.0%
					>90%		65.0%

STSG = split-thickness skin grafting; AMT = autologous non-cultured melanocyte transfer.

The onset of pigmentation in the present study was more or less comparable with that seen in other studies.^8,10,12,13 The earlier onset of pigmentation seen in the AMT group could be due to direct application of melanocyte cell suspension in a nutrient medium, which helped in faster proliferation of melanocytes.

The present study also analysed other factors that influenced the degree of repigmentation such as the anatomical site of the patch, size of the patch, type of vitiligo and duration of stability. In the present study, the patches that achieved better repigmentation were located on the limbs and acral parts in both the groups, but slightly better results were obtained in the AMT group. Poor repigmentation was seen mostly over patches on flexures in both the groups. This could be due to difficulty in immobilisation and effective pressure dressing of the flexural areas, leading to poor graft uptake. Hence, none of these two methods are suitable for flexural areas. AMT was noted to be particularly suitable for joints in this study. The trunk and extremities showed the best response in both the groups in various other studies too.^7,8,9,14 However, the study by Olsson et al.⁷ showed that joints, hands and feet were the most difficult areas to repigment. Similarly, poor results over acral parts were also seen by Sobhy et al.,⁸ Talukdar et al.⁹ and Pandya et al.,¹⁴ which is in contrast to those seen in the present study.

Segmental patches and patches with longer duration of stability (more than two years) showed overall better response in terms of repigmentation irrespective of the method. Other studies^7,8 also demonstrated similar results. The presence of melanocyte-specific T lymphocytes and autoantibodies in vitiligo vulgaris can interfere with the outcome of transplantation. No autoimmune component is involved in the aetiology of segmental vitiligo, and it stabilises spontaneously within the first year of onset; hence, this type of vitiligo has the best surgical outcome.^7,8

The donor-to-recipient area ratio in the AMT group in the present study was similar to that in other studies.^5,12,15 Expansion up to 10 times by dilution of the cell suspension has been done for treating larger recipient areas by Mulekar et al¹¹ and Paul.¹² Pigmentation at the treated areas gradually increased in size owing to melanocyte proliferation and migration under the influence of cytokines secreted by the surrounding keratinocytes. Hence, melanocytes taken from a small donor area could pigment a much larger recipient area.

Few complications were seen on recipient areas in case of STSG. Colour mismatch was also observed by Sobhy et al.,⁸ and milia formation has been reported by Njoo et al.¹⁶ Perigraft halo was observed by Olsson et al.⁷ and Majid et al.¹⁰ as well. Sameem et al¹³ commented that the thickness of the graft was a defining factor for the satisfactory response. Thinner grafts that shed off completely after donating the melanocytes to vitiliginous areas are preferred to thicker grafts, which would result in a stuck-on appearance at the recipient site. In the present study, the donor graft was harvested using a novel dermatome (Sobers dermatome), which had the advantage of obtaining a thin graft of uniform thickness by adjusting the angle at which the dermatome is held to the skin surface. Thus, the ‘stuck-on appearance’ was not seen in this study. Obtaining a thin graft is equally important in AMT also as it eases dermoepidermal separation.

In comparison, the AMT group had much less complications and cosmetically better outcomes. Colour matching was better in this method as the cells are diluted and are transplanted in smaller numbers than in the other methods of transplantation.⁷ Another complication noted in this study was maceration of the recipient site in AMT. This occurred owing to deeper dermabrasion, leading to collection of serous fluid underneath the dressing at the dermabraded site. Hence, only superficial dermabrasion is advised for AMT.

Njoo et al.¹⁶ compared the results of various individual studies on surgical autologous transplantation methods available in the literature. In their review, they found the highest success rates were achieved with split-thickness grafting (87%) and epidermal blister grafting (87%). The lowest success rate was reported with grafting of non-cultured epidermal suspension (31%). However, of the latter, only 16 patches were studied, and this analysis was carried out more than 20 years back when autologous melanocyte-grafting technique was in its evolving stage.

Conclusions

Surgical treatment of vitiligo is suitable for patients having stable disease. Both STSG and AMT are effective surgical modalities in the management of stable vitiligo. Although there is no statistically significant difference in the degree of repigmentation between the two groups, the AMT group exhibited a faster onset of pigmentation and a cosmetically better outcome with uniform pigmentation and better colour and textural matching than the STSG group. The advantages of AMT over STSG are the smaller size of the donor area required and minimal complications over both recipient and donor areas. The disadvantage of AMT is that it is time-consuming, requires expertise, specific equipment and expensive chemical reagents that require storage at subzero temperatures. It is recommended that further research studies must be carried out on a larger number of vitiligo sites and that the operated sites be followed up for a longer period for evaluation of the efficacy, long-term status of repigmentation and complications of both the modalities.

Disclosure of competing interest

The authors have none to declare.