Cath Lab Digest

Biological extracellular matrices may play a valuable role in reducing potential complications and facilitating improved wound healing. Accordingly, these authors review the literature, discuss key considerations with the use of these products in chronic wounds, and share their insights on the potential of an emerging xenograft.

   Chronic wounds in the lower extremities pose a significant healthcare problem. Complications of foot ulcers are the leading cause of hospitalization and amputation in patients with diabetes mellitus.¹ Researchers have estimated that 50 percent of patients suffering from venous ulcers have an ulcer duration of greater than one year. These ulcers have generally proven to be more difficult to manage and also require more time to heal.^2-4

   A variety of treatment modalities are available for the treatment of these difficult wounds.⁵ Topical dressings, ointments, medications, devices and other external products offer varying benefits depending on the nature of the wound environment. Studies that have been published are predicated on the inhibition and/or modulations of biologic markers that are altered in chronic wounds.⁶ Regardless of the treatment modality one utilizes, creating and optimizing the wound environment by facilitating cellular activity may be of significant benefit in promoting wound closure.⁷

   Biological extracellular matrices (ECMs) may consist of allogenic, xenogenic or chemical constructs that act as temporary matrices that the host tissue eventually replaces. These products provide a structure for cell migration and activity that is absent in many full-thickness defects.

   Clinicians have used a variety of these matrices in wound care settings and some authors have had clinical success with regard to reducing the time to healing and improving the wound healing rate.^8,9

   In a prospective, randomized trial, Marston and colleagues found that Dermagraft (Advanced Biohealing), in comparison to conventional therapy, had significant benefit over a 12-week period in patients with chronic diabetic foot ulcerations greater than six weeks in duration.⁸

   In a randomized multicenter trial involving over 200 patients, with non-infected, neuropathic diabetic foot ulcers, Veves and co-workers compared Apligraf (Organogenesis) to saline-moistened gauze.⁹ Researchers provided extensive surgical debridement and adequate foot offloading to both groups. The study authors found that 56 percent of patients treated with Apligraf achieved complete wound healing at 12 weeks in comparison to 38 percent of the saline-moistened gauze group.

   In a review of collagen-based materials, Ehrenreich and Ruszczak have identified several important attributes that would ensure the best clinical success of a tissue-engineered biologic wound dressing. Although these authors say there is a lack of universal consensus on the mechanism of action of these products, they cite the delivery of growth factors and extracellular matrix components to the wound as “important” in facilitating healing.¹⁰

   Along these lines, we would like to present our experience and approach to treating these chronic wounds with xenografts (Unite Biomatrix, Pegasus Biologics). Accordingly, we will offer insights on the makeup of chronic wounds and how xenografts contribute to the wound healing process.

Key Considerations With The Chronic Wound Environment

   Regardless of the etiology of wounds, once an ulcer develops and does not proceed to healing, the chronic wound environment takes on its own unique characteristics. These characteristics include excessive proteases, increased cellular senescence and increased bacterial bioburden.¹¹ Researchers have noted that, at a cellular level, a higher level of matrix metalloproteinase (MMP) production by fibroblasts is one of the factors that contributes to delayed healing with aging.¹²