Archangels first invested in Tissue Science Laboratories plc (TSL) in 2000 and the company floated on AIM in December 2001. It was subsequently acquired by Covidien in 2008, who were then purchased by Medtronic in 2015.

TSL developed products for the surgical implant and wound care market. Its first product was Permacol Surgical Implant, a flat sheet collagen matrix derived from porcine dermis. Intended for use in surgical operations in the fields of urology and gynaecology, head and neck recontouring and general surgery in hospitals across Europe and the US. TSL products were designed to be strong, non-allergenic, natural repair materials, to remain permanently in patients and support formation of new cells and blood vessels.