Gastrointestinal (GI) fistula is a complex condition with high mortality and requiring a multidisciplinary management.

The aim of this study is to exploit the regenerative-tissue capacities of autologous emulsified adipose tissue-derived stromal vascular fraction (tSVFem, widely used in other medical fields - like plastic surgery -for different purposes) harvested and delivered locally by endoscopy to close the GI fistula.

The proposed technique for the treatment of GI fistulas with tSVFem requires a minimal, inexpensive, easily reproducible mechanical manipulation of autologous adipose tissue without necessity of any enzymatic digestion or cell expansion.

Gastrointestinal fistula may be a life-threatening condition caused by several types of injuries (iatrogenic, traumatic, post-operative), requiring complex and multidisciplinary management. To date, no clear guidelines have been drawn up for the treatment, that may include a conservative, minimally invasive, or major surgical approach depending on the patient's specific clinical characteristics. Furthermore, patients with fistulas are often fragile, and surgical treatments are highly risky and invasive. Less invasive treatments such as stenting, endoluminal endoscopic vacuum therapy and suturing are widely employed, but these treatments often require long hospitalization, highly skilled operators, without certain results and with high rates of complications.

The aim of this study is to exploit the regenerative-tissue capacities of autologous emulsified adipose tissue-derived stromal vascular fraction (tSVFem, widely used in other medical fields - like plastic surgery -for different purposes) harvested and delivered locally by endoscopy to close the GI fistula. Indeed, the anti-inflammatory and regenerative-tissue promoting effects of tSVFem may safely promote rapid and effective tissue healing as alternative, and in this setting they were not investigated before. Fistulas are often long-standing chronic conditions, thus healing mechanisms are delayed and subverted in favor of inflammation and fibrosis, resembling chronic inflammatory diseases. Delivery of tSVFem is a promising new approach that promotes healing in virtue of its immunosuppressive, immunomodulatory, pro-angiogenic and regenerative potentials. Since the grafted material used in this study is autologous, there is no risk for rejection. All the procedures are performed under general anesthesia with orotracheal intubation or laryngeal mask. Approximately 30 cc of fat are harvested from the superficial layer of subcutaneous tissue by a 2.1 mm microcannula with 4, 1-mm size holes, arranged in a single raw, to get the so-called "microfat". Twenty cc of the harvested microfat are mechanical emulsified by sequential passages through 2.4mm and 1.2mm filters, and a 600/400 μm disposable filtering device.

Then the material is centrifuged at 3000 rounds for three minutes, obtaining the tSVFem after removal of supernatant fraction and oil released upon mature adipocytes mechanical disruption.

Subsequently, an endoscopy is performed to inject 10 cc of microfat into the fistula (through a 6-French catheter) until it was completely filled. Then, with a 22 Gauge endoscopic needle, a total of 1-2 cc of tSVFem were injected into the submucosa of the 4 quadrants of the fistula borders, to obliterate it completely.

A radiologic and endoscopic control at day-7 is done to evaluate complete healing of the fistula.

The technique proposed by the investigators for the treatment of GI fistulas with tSVFem requires a minimal, inexpensive, easily reproducible mechanical manipulation of autologous adipose tissue without necessity of any enzymatic digestion or cell expansion.

Inclusion criteria:

• Patients affected by GI fistulas, not fit for surgical treatments of after failure of conventional conservative treatments

Exclusion Criteria:

• Enteroenteric fistulas
• Patients who do not sign informed consent form