Microsurgery Without Sutures Using A Refined Poloxamer Gel Stent
Christopher R. Davis, BSc, MB ChB, MRCS1; C Travis Rappleye, MS1; Peter A. Than, MD1; Melanie Rodrigues, PhD1; Sarah N. Bishop, MD1; Arnetha J. Whitmore, BA1; Zeshaan N. Maan, MD1; Sacha Khong, PhD1; Rory B. McGoldrick, MBA, FRCS1; Shadi Ghali, FRCS2; Adriaan O. Grobbelaar, FRCS1; Daniel Navarrete, 1 Jayakumar Rajadas, PhD1; Gerald G. Fuller, PhD1; Geoffrey C. Gurtner, MD, FACS1
1Stanford Univeristy, Stanford, CA, USA, 2Royal Free Hospital, London, United Kingdom
PURPOSE: Poloxamers are thermoreversible biomaterials with translational clinical application as microvascular stents for sutureless anastomoses using surgical adhesive. This research aimed to refine poloxamer formulations and create a thermoreversible stent for optimal clinical application.
METHODS: Poloxamer formulations of varying concentrations of P407, P188 and bovine serum albumen (BSA) were tested for strength and transition temperature. In vitro rheological testing and determination of elastic moduli was performed on a stress rheometer. Formulations were tested whilst incrementally decreasing temperature from 40°C to 15°C. In vivo testing was performed in a rat model.
RESULTS: Pure P188 at 45% concentration is the strongest poloxamer with the sharpest inter-state transition (Table). Pure P188 has a poloxamer concentration of 45%, does not require BSA, and transitions at 25°C with a strength of 96kPa. This poloxamer permits liquid intravascular injection, with immediate solidification on contact with warmer vasculature, before return to liquid form after dissolution from releasing microvascular clamps. In vivo application demonstrated liquid-gel ooze at lower concentrations and semi-solid gel stent after optimization (Figure)
CONCLUSIONS: P188 has ten-times the strength of previous formulations, precise binary state-transition, and does not require BSA. This FDA-approved biomaterial can be used for safe and successful sutureless microvascular anastomoses.
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