Tissue regenerative and xenograft biotherapy: helping surgeons to save lives, and limbs
By Dr. Abdullah Jibawi
Image credit: CC0 Public Domain via Pixabay.
Surgeons have been facing an ever increasing crisis in finding a suitable material that can replace failing organs and blocked vessels safely and effectively. The worldwide shortage of organs causes almost 30% of patients who need replacement organs to die on the waiting list. Certain procedures such as bypass surgery and certain types of large incisional hernia repairs have a high success rate when performed using natural material such as the patient’s own veins. However, where this option is unavailable (due to already diseased veins for example), the success rate drops significantly as a plastic material is used instead. Pooled weighted data for primary patency rates for femoro-distal bypass are reported as 85%, 80%, and 70% for femoro-distal bypass with vein and 70%, 35%, and 25% for femoro-distal bypass with prosthetic material at 1, 3, and 5 years respectively.
Human xenotransplantation (read this freely available chapter), the transplantation of partial or complete living tissues/organs from non-human species to humans, offers a potential alternative to plastic material for failed organs and blocked vessels in humans, while also raising many novel medical, legal, and ethical issues. A more advanced methodology of using xenografts is the creation of acellular scaffolding material from animal tissue that avoids the immune rejection while maintaining the strength and original natural structure of the living body. XenMatrix™ Grafts, for example, are created using a process which effectively removes cells from porcine (pig) collagen while maintaining the structure and strength of the graft. The resulting open collagen scaffold allows early cellular infiltration and revascularization without a significant loss of strength during the early healing process.
Omniflow II biosynthetic vascular graft, on the other hand, is a composite of cross-linked ovine (sheep) collagen with a polyester fine plastic mesh endoskeleton. The polyester mesh provides strength and durability, with resistance to aneurysm formation, while the collagen is stabilized, non-antigenic, and remains structurally intact for years after implantation. The wall revascularization improves resistance to infection.
Finally, the US Food and Drug Administration (FDA) approved earlier this year a new indication for the Integra Omnigraft Dermal Regeneration Matrix to treat diabetic foot ulcers. The matrix, which is made of silicone, cow collagen, and shark cartilage, is placed over the ulcer and provides an environment for new skin and tissue to regenerate and heal the wound.
In our centre - the Ashford and St Peter's Hospital NHS Foundation Trust - the vascular surgeons have been using the above mentioned technologies on selected patients where all other alternatives have been deemed inappropriate by the multidisciplinary team. We have used XenMatrix™ Grafts recently on a large incisional hernia repair where the bowel was exposed under the skin, making the use of plastic material too dangerous and risking bowel erosion with subsequent contamination. The patient did very well and has regained her quality of life successfully. We have also used Omniflow II biosynthetic vascular graft in many other patients where the risk of infection was substantive and the options for using veins were limited. Those patients recovered well and regained excellent blood flow to their legs. Finally, the Surrey Tissue Viability Board will be soon considering Dermal Regeneration Matrix obtained from fish skin to treat difficult to heal wounds in selected cases where all other methods have failed to achieve acceptable level of wound healing.
We strongly believe that the technology of xenografts is here to stay, and is certainly the way forward if we are to win the continuous battle against resistant infection, shortage of organs, and increasing need for creative but naturally-driven solutions in disease management.
Dr. Abdullah Jibawi is a consultant vascular, endovascular and general surgeon and a specialty lead for vascular surgery at the Ashford and ST Peter’s hospital NHS foundation trust. He is the co-author of Current Surgical Guidelines, which provides a concise and easily-accessible summary of all currently available guidelines in surgery: available in print and online.
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