The wounding event—whether caused by trauma or by a surgical procedure—leads to damage of blood vessels, which initiates a clotting cascade involving complement factors in the blood, resulting in the formation of fibrin clots. This clotting cascade also helps to block pathogens from accessing the blood or tissues at the injury site. Vasoconstriction occurs to aid the biochemical cascade and cause hypoxia, which attracts white blood cells into the tissue and causes a humoral and cellular inflammatory response. This occurs extremely quickly and leads to the release of vasoactive factors such as histamine and bradykinin; these maintain the flow of blood factors to deal with the damaged tissue and any pathogens at the wound site. Wound exudates are allowed to seep through to the damaged area carrying inflammatory immune factors for repair. Plasma factors, including lysozyme, white blood cells (WBC) and macrophages, then begin the process of removing dead cells and debris from the tissue. Macrophages and WBC play an important role in regulating the healing process through cytokines and growth factors.
Hemostasis is a general term given to the process which is initiated to stop the bleeding and thus prevent significant loss of blood, and to close the wound and block the entry of pathogens as quickly as possible. Central to hemostasis is the clotting process; denatured polymers such as collagen and other foreign bodies in the injured site activate substances known as complement factors in the blood; these act on a soluble, blood-borne thrombin precursor (prothrombin) to cause it to change to thrombin. Thrombin brings about the cleavage of the protein fibrinogen to form an insoluble fibrin clot; fibrin is then further cross-linked by an enzyme in blood called Factor XIII. The cascade of events also results in the release of vasoactive factors to accelerate blood clotting.
The extent of the clotting process, the biochemical makeup of the hemostasis cascade, and the density of the fibrin clot are dictated by a combination of genetic and environmental factors. It is thought that the clotting process has evolved, over many millennia of evolutionary development, to be very efficient at stopping bleeding rapidly, preventing infection, and stimulating repair, albeit at some cost in terms of the resultant cosmetic appearance of the healed skin.
The development of products that provide hemostasis as a step in wound management is perhaps less challenging that many other wound management product segments. After all, the human body has been evolutionarily designed with its own clotting pathway in order to stem the flow of blood from vasculature. Indeed, virtually all products on the market and in development seek to capitalize on the existing clotting cascade, or replicate it in product form, in order to stop bleeds.
Products for hemostasis may include one or more of the following components: thrombin, gelatin, collagen, fibrin, synthetic and other materials, and there are many companies pursuing the development and marketing of each of these product types (see link). Globally, the market for these products stands at nearly $3 billion and is expected to grow to over $4.5 billion by 2017.
There are more than forty (40) active companies in the market for hemostatic products.
(See “Worldwide Surgical Sealants, Glues, Wound Closure and Anti-Adhesion Markets, 2010-2017”, Report #S190, for a complete analysis of these products.)