JSUR Journal

Introduction

The aim of this clinical study is to determine the safety and efficacy of autologous adipose-derived stem cells for the treatment of perianal fistula. Minimally invasive surgery of perianal fistulas has become increasingly important in recent years, especially in the use of autologous stem cells. The immunomodulatory and anti-inflammatory capabilities of adipose-derived stem cells could contribute to the healing process of the fistula [1].

Materials and Methods

This study was conducted in accordance with the rules of the STROBE Statement (Strengthening the reporting of observational studies in epidemiology). The sample size included 18 patients whose data were recorded in an anonymous database. All were

admitted and treated at the Oncological Surgery Department - Garibaldi Nesima - Italy, from November 2022 to February 2023. Briefly, all patients presented with a recurrent and/or complex perianal fistula, with or without Chron’s disease. Patients provided informed consent for data recording within our database in an anonymous form. The diagnosis of perianal fistula was made by examination (MRI of the pelvis) in all patients. Treatment results were assessed by the operator at 2, 4, 6 and 12 weeks after treatment. Healing was defined as the absence of drainage through the external openings and the complete re-epithelialisation of these openings, as well as the absence of pain. A retrospective clinical study was conducted by obtaining data from the pre-filled database. Patients were enrolled from November 2022 to February 2023. During the screening visit 18 patients were divided into two groups A (control) and B (experimental). The groups were created taking into account the patients’ data to minimise bias.

Group A included 8 patients (male:female, M:F=1.6) who had received ‘Standard surgery’, consisting on excision of fistula up to the previously specillated internal orifice; the internal orifice was obliterated using mucosal flap and sutures. Group B included patients who had received ‘Standard Surgery and injection of autologous Adipose-Derived Stem Cells (ASCs)’ with 10 patients (M:F=0.66). The surgery group was the same in both groups and the same group then evaluated the patients in follow-up for 2, 4, 6 and 12 weeks after treatment. At least 4 weeks before surgery, all patients underwent drainage seton. Subsequently, during the same operating session, patients in group B underwent liposuction for ASCs.

Liposuction was performed by the same surgical team under local anaesthesia, obtaining at least 200 ml of lipoaspirate. This material was subsequently processed in a Matrigen^® filtration system directly in the operating room. The final dose of ASCs was approximately 40 ml prepared in ready-to-use syringes. The adipose preparation was subsequently administered in the operating room according to a standard surgical protocol, as described in ‘A Step-By-Step Surgical Protocol for the Treatment of Perianal Fistula with Adipose-Derived Mesenchymal Stem Cells’, and with external control during the surgical procedure in all cases. Briefly, prior to the injection of ASCs (group B), the excision of all via fistula up to the previously specillated internal orifice was performed. The internal orifice was obliterated using mucosal flap and sutures. Half of each dose was injected around the inner opening and the other half through the outer opening. Finally, the external wound was sutured with detached silk stitches. Clinical evaluation of fistula healing was assessed at 2, 4, 6 and 12 weeks after treatment. The incidence of Adverse Events (AE) and Serious Adverse Events (SAE) was assessed at each follow-up visit. The operating surgeon assessed healing at weeks 2, 4, 6 and 12. Healing was defined as the absence of drainage through the external wound and its complete re-epithelialisation in the absence of pain. Considering the effective results obtained and recorded in our database, we requested the ethics committee’s permission to perform a retrospective study to perform a long-term (ongoing) follow-up of the patients included in the study, with a focus on longterm safety, recurrence of healed fistulas, and to determine the final status of healing and perianal suppuration. The data were expressed as mean ± standard deviation. The results were analyzed using Statistica^® v.10 software and significance was calculated using the Student’s t and Chi-square method.

Results

This retrospective clinical study was designed to determine the efficacy of a new standardised and monitored surgical procedure using ASCs for the treatment of perianal fistula. ASCs were chosen both because the stem cells and their anti-inflammatory effects promote long-term healing and for their excellent safety profile. As shown in Figure (indicate number), 18 patients with perianal fistula were enrolled and divided into two groups: Group A underwent ‘standard surgery’ (8 patients, male:female M:F=1.6); Group B underwent ‘surgery with ASCs’ (10 patients, M:F=0.66). Group A comprised patients aged between 20-52 years; the average age was 34 years (Figure 1).

Figure 1: Graphical summary of statistical analysis of age group A patients.

Through statistical analysis, the lower and upper quartile of the age of the Group A patients was calculated. The first was 27.00 while the second was 40.50, the minimum being 20.00, the median 32.50 and the maximum 52.00. Finally, the standard deviation value was 10.68 (Figure 2).

Figure 2: Graphical summary of statistical analysis of age group A patients.

As for Group B, it comprised patients aged between 18-50 years, in fact the average age was 29.2 years (Figure 3).

Figure 3: Graphical summary of statistical analysis of age group B patients.

Statistical analysis revealed that the lower quartile corresponded to 21.00, while the upper quartile corresponded to 40.00, the minimum being 18.00, the median 24.00 and the maximum 50.00. Finally, the standard deviation value was 11.18 (Figure 4).

Figure 4: Graphical summary of statistical analysis of age group B patients.

All patients followed-up at 2, 4, 6 and 12 weeks after treatment. After 12 weeks significant differences were found between patients in group A and those who received the ASCs (group B). Thus, the results show that the fistula healing rate 12 weeks after the first treatment was 62.50% (95% CI; 5 out of 8 patients) for group A and 80.00% (95% CI, 21.8-65.9; 8 out of 10 patients) for group B (Figure 5). Therefore, surgical treatment with ASCs showed a significant increase of 17.5% of patients healed already after 12 weeks compared to treatment with standard surgery. However, cases of recurrence were recorded with both surgical treatments. Indeed, after 12 weeks of follow-up, a significant change was observed, as two out of eight healed patients in group A (25.00%; CI: 95%) experienced recurrence compared to only one out of 10 patients in group B (10.00%; CI: 95%) (Figure 5).

Figure 5: Flow-chart: enrollment, allocation and follow-up. ASCs: Autologous adipose-derived stem cells.