Intravenous allogeneic umbilical cord blood-derived mesenchymal stem cell therapy in recessive dystrophic epidermolysis bullosa patients

Abstract

BACKGROUNDRecessive dystrophic epidermolysis bullosa (RDEB) is an incurable disease that causes severe mucocutaneous fragility due to mutations in COL7A1 (encoding type VII collagen [C7]). In this phase I/IIa trial, we evaluated the safety and possible clinical efficacy of intravenous infusion of allogeneic human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in patients with RDEB.METHODSFour adult and two pediatric patients with RDEB were treated with 3 intravenous injections of hUCB-MSCs (1 × 106 to 3 × 106 cells/kg) every 2 weeks and followed up for 8-24 months after treatment. The primary endpoint was safety. Secondary endpoints related to efficacy included clinical parameters, such as disease severity score, wound assessment, itch and pain score, and quality of life. C7 expression levels and inflammatory infiltrates in the skin, as well as serum levels of inflammatory markers and neuropeptides, were also assessed.RESULTSIntravenous hUCB-MSC infusions were well tolerated, without serious adverse events. Improvements in the Birmingham Epidermolysis Bullosa Severity Score, body surface area involvement, blister counts, pain, pruritus, and quality of life were observed with maximal effects at 56-112 days after treatment. hUCB-MSC administration induced M2 macrophage polarization and reduced mast cell infiltration in RDEB skin. Serum levels of substance P were decreased after therapy. Increased C7 expression was observed at the dermoepidermal junction in 1 of 6 patients at day 56.CONCLUSIONTo the best of our knowledge, this is the first clinical trial of systemic administration of allogeneic hUCB-MSCs in patients with RDEB, demonstrating safety and transient clinical benefits.TRIAL REGISTRATIONClinicalTrials.gov NCT04520022.FUNDINGThis work was supported by Daewoong Pharmaceutical Co. Ltd. and Kangstem Biotech Co. Ltd.

Keywords: Clinical Trials; Dermatology; Genetic diseases; Skin; Stem cell transplantation.

Conflict of interest statement

Conflict of interest: KR works in the Department of Clinical Development of Kangstem Biotech Co. Ltd., a biotechnology company focused on stem cell therapeutics. KK and BC work in the Cellular Therapeutics Team at Daewoong Pharmaceutical Co. Ltd.

Figures

Figure 1. Study design.

(A) Flow chart for clinical trial and treatment use (expanded access to investigational drugs for treatment use). (B) Study design for hUCB-MSC treatment and evaluation.

Figure 2. Marked reduction in erythema and erosions after hUCB-MSC treatment.

Photographs of a pediatric (A, subject 4) and an adult patient with RDEB (B, subject 1) at baseline and after 3 repeated injections of hUCB-MSCs.

Figure 3. Systemic treatment with hUCB-MSCs improved clinical symptoms in patients with RDEB.

The time course of changes in disease severity (assessed by Birmingham Epidermolysis Bullosa Severity Score [BEBSS]), blister count, visual analog scale (VAS) pain score, and VAS pruritus score was assessed throughout the trial. For each parameter, a graphical representation of mean score per visit with range per visit was added. Two-tailed Student’s t test was performed for all the comparisons (n = 6). *P < 0.05. S, subject. Values are shown as the mean ± SEM.

Figure 4. Systemic treatment with hUCB-MSCs does not significantly affect the expression levels of C7 at the DEJ in most patients, except for in 1 patient (subject 1), who showed an increase in C7 expression at day 56.

(A) Representative immunofluorescence staining for type VII collagen (C7) using LH7.2, a monoclonal antibody that recognizes the NC1 domain of C7, on skin biopsy samples obtained before treatment (baseline) and at day 56 from patients with RDEB (subjects 1 and 5) receiving hUCB-MSC treatment. Scale bars: 20 μm. White arrows indicate C7 expression at the dermoepidermal junction (DEJ). (B) The intensity of staining for C7 expression along the DEJ was morphometrically quantitated as MFI using ImageJ (NIH). Values are shown as the mean ± SEM.

Figure 5. hUCB-MSC treatment modulates macrophage phenotype and mast cell infiltration in skin from patients with RDEB.

(A) Representative immunofluorescence staining for total macrophages (CD68), CD206+ macrophages, and mast cells (c-kit) on skin biopsy samples before treatment (baseline) and at day 56 for 6 matched pairs of patients with RDEB receiving hUCB-MSC treatment. Scale bars: 50 μm. (B) Mean total numbers of skin-infiltrating cells in biopsies from healthy controls (HCs) and RDEB skin at day 0 and at day 56 following hUCB-MSC treatment. By day 56, hUCB-MSC treatment markedly increased CD206+ macrophage counts and reduced mast cell counts. Values are shown as the mean ± SEM. Wilcoxon’s signed-rank test was performed for all the comparisons (n = 6). ***P < 0.001. S, subject.

Figure 6. hUCB-MSC treatment reduces serum substance P levels in patients with RDEB.

Serum levels of inflammatory cytokines (IL-1β and IL-6) and neuropeptides (substance P and CGRP) were assessed in healthy controls (HCs) and patients with RDEB (n = 6) at baseline and at day 56 following hUCB-MSC treatment. Values are shown as the mean ± SEM. Wilcoxon’s signed-rank test was used to assess the statistical difference between the repeated measurements in the same patient. *P < 0.05. S, subject.