A Reliable Porcine Fascio-Cutaneous Flap Model for Vascularized Composite Allografts Bioengineering Studies

Summary

The present protocol describes the porcine fascio-cutaneous flap model and its potential use in vascularized composite tissue research.

Abstract

Vascularized Composite Allografts (VCA) such as hand, face, or penile transplant represents the cutting-edge treatment for devastating skin defects, failed by the first steps of the reconstructive ladder. Despite promising aesthetic and functional outcomes, the main limiting factor remains the need for a drastically applied lifelong immunosuppression and its well-known medical risks, preventing broader indications. Therefore, lifting the immune barrier in VCA is essential to tip the ethical scale and improve patients' quality of life using the most advanced surgical techniques. De novo creation of a patient-specific graft is the upcoming breakthrough in reconstructive transplantation. Using tissue engineering techniques, VCAs can be freed of donor cells and customized for the recipient through perfusion-decellularization-recellularization. To develop these new technologies, a large-scale animal VCA model is necessary. Hence, swine fascio-cutaneous flaps, composed of skin, fat, fascia, and vessels, represent an ideal model for preliminary studies in VCA. Nevertheless, most VCA models described in the literature include muscle and bone. This work reports a reliable and reproducible technique for saphenous fascio-cutaneous flap harvest in swine, a practical tool for various research fields, especially vascularized composite tissue engineering.

Introduction

Vascularized composite allografts (VCA) have revolutionized the treatment of hard-to-repair body part losses, such as hands, face, and penis^1,2,3. Unfortunately, the first long-term outcomes⁴ have shown that lifelong administration of high-dose immunosuppressive agents can lead to severe collateral medical conditions, including diabetes, infections, neoplasia, and reno-vascular dysfunction⁵. Lately, expert VCA teams have had to manage the risk of chronic rejection leading to graft loss and perform the first face retransplantatio....

Protocol

All animals received human care following the National Institute of Health Guide for the Care and Use of Laboratory Animals. The Institutional Animal Care and Use Committee approved the experimental protocol (IACUC- protocol #2020N000015). Seven female Yorkshire pigs (20-25 kg) were used for all experiments.

1. Preoperative care

1. Fast the animal for solid food 12 h prior to the surgery.
2. Sedate the animal with 4.4 mg/kg of Telazol, 2.2 mg/kg of Xylazine, an.......

Discussion

This article describes a reliable and reproducible fasciocutaneous flap harvested on swine hindlimbs. Following this step-by-step surgical protocol will allow the procurement of two flaps on only one animal in less than 2 h. The most critical step of the surgery is the skeletonization of the vascular pedicle within the gracilis muscle fibers, which requires a thorough dissection by a skilled surgeon. Securing the skin to the fascia using cutaneous sutures is a crucial tip to avoid a shearing effect disrupting the perfora.......

Materials

Name	Company	Catalog Number	Comments
18 G angiocatheter	BD Insyte Autoguard	381409
20 G angiocatheter	BD Insyte Autoguard	381411
Adson Tissue Forceps, 11 cm, 1 x 2 Teeth with Tying Platform	ASSI	ASSI.ATK26426
Atropine Sulfate	AdvaCare	212-868
Bipolar cords	ASSI	228000C
Buprenorphine HCl	Pharmaceutical, Inc	42023-179-01
Dilating Forceps	Fine science tools (FST)	18131-12
Endotrachel tube	Jorgensen Labs	JO615X	size from 6 to 15mm depending on the pig weight
Ethilon 3-0 16 mm 3/8	Ethicon	MPVCP683H
Euthasol	Virbac AH	200-071
Heparin Lock Flush Solution, USP, 100 units/mL	BD PosiFlush	306424
Isoflurane	Patterson Veterinary	14043-704-06
Jewelers Bipolar Forceps Non Stick 11 cm, straight pointed tip, 0.25 mm tip diameter	ASSI	ASSI.BPNS11223
Metzenbaum scissors 180 mm	B Braun	BC606R
Microfil blue	Flow tech	LMV-120
Microfil dilution	Flow tech	LMV-112	colored filing solution
Monopolar knife	ASSI	221230C
N°15 scalpel blade	Swann Morton	NS11
Omnipaque	General Electric	4080358	contrast product
Perma-Hand Silk 3-0	Ethicon	A184H
Small Ligaclip	Ethicon	MCM20
Stevens scissors 115 mm	B Braun	BC008R
Telazol	Zoetis	106-111
Xylamed (xylazine)	Bimeda	200-529