Essential Insights On Bioengineered Alternative Tissues

Ryan H. Fitzgerald, DPM, Paul J. Kim, DPM, and John S. Steinberg, DPM

While bioengineered alternative tissue (BAT) products show promise in the management of complicated lower extremity ulcerations, the variety of these emerging modalities can lead to confusion on appropriate indications and proper use. Accordingly, these authors provide a timely update, suggest the use of new terminology and survey the most recent literature on the efficacy of BAT modalities.

   As physicians, we are facing a rising epidemic of limb loss due to the development of diabetic foot ulcerations (DFU). The consequences of major amputation in the lower extremity are well understood. Recent data suggests that the morality rate associated with lower extremity amputation indeed rivals most cancers.1

   In addition to advances in interdisciplinary treatment protocols that allow for rapid diagnosis and management of complex wounds in this high-risk patient population, there have been advances in bioengineering and a transition toward greater evidence-based research. These advances have provided the practitioner with numerous new technologies that can facilitate predictable healing for wounds in patients who previously would have faced the threat of limb loss.

   Additionally, as we have gained greater clarity on the etiologies for wound development and chronicity, we have seen the emergence of treatment modalities that can help address the specific local and systemic factors that can impede wound healing.

   While the development of these technologies serves as a windfall in the treatment of complex lower extremity ulcerations, the sheer numbers and variety of wound healing products that have become available in the last few years have led to some confusion. As a result, there may be hesitancy on the part of many physicians who consider using these products for their patients.

   A key point of confusion in the arena of new wound technologies begins with the labeling and terminology used to describe these products. We previously introduced a new term, “bioengineered alternative tissue” (BAT), which more accurately encompasses and describes these wound care products, and will help direct their use.

   While these products fill a specific niche in wound care, none of them is a panacea. Obviously, no one product will work for all types of wounds. While there is some overlap between these products, the greatest likelihood for successful wound healing lies with thorough wound evaluation and appropriate product selection.

A Primer On Wound Healing Fundamentals

   Within the context of wound healing, there are four important components: epidermis, dermis, hypodermis (subcutaneous adipose tissue) and underlying tissue. The epidermis is the most superficial component of skin. It has no direct vascular supply and sloughs continuously. The dermis is often regarded as the most important skin component to wound healing and it is at this layer that clinicians look for granulation tissue.

   The skin contains important growth factors (e.g. vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF)) that stimulate tissue repair and angiogenesis during the process of wound healing. Bioengineered alternative tissues generally stimulate these processes in the wound bed or can often serve to deliver growth factors extrinsically when one applies these tissues to the wound. Some BATs contain living fibroblasts and keratinocytes in addition to growth factors. These living cell components can play an important role through the continued production of growth factors after their delivery to the wound bed and help to stimulate the development of granulation tissue.

   When selecting a particular BAT product, it is important to keep in mind the different layers of tissue and their aforementioned architecture. In many cases, one can choose a specific product to match the wound depth and nature. Proper selection of BAT products increases the likelihood of successful wound closure.

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