Wound Debridement by Continuous Streaming of Proteolytic Enzyme Solutions: Effects on Experimental Chronic Wound Model in Porcin

Author(s): 
Tali Yaakobi, PhD; Noa Cohen-Hadar, PhD; Hila Yaron, MSc; Eran Hirszowicz, MSc; Yariv Simantov, VMD; Arie Bass, MD; Amihay Freeman, PhD

Chronic limb wounds are associated with tissue ischemia and are typical in patients with diabetes. Such wounds can lead to serious infection, gangrene, and limb loss. Chronic wounds are characterized by the presence of devitalized tissue that enhances bacterial growth, reduces host resistance to infection, and inhibits the formation of granulation tissue.1–3 Debridement of necrotic tissue is therefore, an essential and crucial step in chronic wound management.4–7 The main approaches to wound debridement are based on surgical, mechanical, enzymatic, or biological methods.3,6,8,9
Enzymatic removal of necrotic tissue from chronic wounds and burns by proteases primarily offers selectivity of debridement without impairing adjacent healthy tissue.10,11 Proteolytic enzymes for wound debridement are commercially available as ointments.10 The most frequently used products that contain papain are Accuzyme9 (Healthpoint, Fort Worth, Tex) and Panafil11,12 (Healthpoint, Fort Worth, Tex). Comparative preclinical and clinical studies on the efficacy of papain versus other enzyme ointments indicated that papain was the more effective enzyme from this group. 9,12-14
Papain is a proteolytic enzyme derived from the fruit of Carica papaya, and has been employed for decades in the food and pharmaceutical industries. Furthermore, it was used for many years for wound healing by natives in tropical countries.11,15 Papain is the best studied and most applied protease from the thiol protease family (proteases that have a thiol group playing an essential role in their catalytic mechanism). Therefore, the efficacy of papain’s proteolytic activity is dependent on maintaining its active site’s thiol group in its active form (protection from oxidation, complexation with certain metal ions, or regeneration and pH adjustment to 6–8 are commonly employed means). In many cases, thiol-containing compounds may restore reduced papain activity due to reactions involving its thiol group.
Wound debridement using papain-containing ointments is currently practiced with repeated topical applications over a period of 1–3 weeks. The procedure is both labor intensive and time consuming.12,14 A potential explanation for the reported low efficacy of this mode of papain application for wound debridement is that the environmental conditions created within wounds treated this way are suboptimal or inhibitory to full expression of its potential activity. These conditions include acidic pH values, competitive metal ions, proteases secreted in wound exudate, as well as diffusional limitations imposing limited access of papain to its targeted substrate sites.
The authors previously proposed and demonstrated feasibility of an alternative mode of delivery and application of proteolytic enzymes for wound debridement and cleansing: continuous controlled streaming of protease solutions onto a targeted treated area, providing optimal and controlled environmental conditions for full exploitation of the protease’s potential debridement activity.16 The efficacy of the streaming approach was successfully demonstrated in removal of coagulated blood and debridement of experimental burn wounds in small lab animals by a series of proteases.16

References: 

1. Clark RA. Cutaneous tissue repair: basic biological considerations. I. J Am Acad Dermatol. 1985;13(5 Pt 1):701–725.
2. Mekkes JR, Le Poole IC, Das PK, Bos JD, Westerhof W. Efficient debridement of necrotic wounds using proteolytic enzymes derived from Antarctic krill: a double-blind, placebo-controlled study in a standardized animal wound model. Wound Repair Regen. 1998;6(1):50–57.
3. Enoch S, Harding K. Wound bed preparation: the science behind the removal of barriers to healing. WOUNDS. 2003;15(7):213–229.
4. Nanninga PB, Mekkes JR, Westerhof W. Clinical management of venous leg ulcers. WOUNDS. 1990;2(6):205–212.
5. Hellgren L, Vincent J. Debridement: an essential step in wound healing. In: Westerhof W, ed. Leg Ulcers: Diagnosis and Treatment. Amsterdam, Netherlands: Elsevier Science. 1993:305–312.
6. Ayello EA, Cuddigan JE. Debridement: controlling the necrotic/cellular burden. Adv Skin Wound Care. 2004;17(2):66–75.
7. Falanga V. The chronic wound: impaired healing and solutions in the context of wound bed preparation. Blood Cells Mol Dis. 2004;32(1):88–94.
8. Schultz GS, Sibbald RG, Falanga V, et al. Wound bed preparation: a systematic approach to wound management. Wound Repair Regen. 2003;11(Suppl 1):S1–S28.
9. Wright JB, Shi L. Accuzyme® papain-urea debriding ointment: a historical review. WOUNDS. 2003;15(Suppl 4):2S–12S.
10. Klasen HJ. A review on the nonoperative removal of necrotic tissue from burn wounds. Burns. 2000;26(3):207–222.
11. Falanga V. Wound bed preparation and the role of enzymes: a case for multiple actions of therapeutic agents. WOUNDS. 2002;14(2):47–57.
12. Hebda PA, Flynn KJ, Dohar JE. Evaluation of the efficacy of enzymatic debriding agents for removal of necrotic tissue and promotion of healing in porcine skin wounds. WOUNDS. 1998;10(3):83–96.
13. Hebda PA, Lo C. The effects of active ingredients of standard debriding agents—papain and collagenase—on digestion of native and denatured collagenous substrates, fibrin and elastin. WOUNDS. 2001;13(5):190–194.
14. Alvarez OM, Fernandez-Obregon A, Rogers RS, Bergamo L, Masso J, Black M. A prospective, randomized, comparative study of collagenase and papain-urea for pressure ulcer debridement. WOUNDS. 2002;14(8):293–301.
15. Pieper B, Caliri MH. Nontraditional wound care: a review of the evidence for the use of sugar, papaya/papain, and fatty acids. J Wound Ostomy Continence Nurs. 2003;30(4):175–183.
16. Yaakobi T, Roth D, Chen Y, Freeman A. Streaming of proteolytic enzyme solutions for wound debridement: a feasibility study. WOUNDS. 2004;16(6):201–205.
17. Forbes PD. Vascular supply of the skin and hair in swine. In: Montagna, W, Dobson RL, eds. Advances in Biology of the Skin. New York, NY; Pergamon Press: 1969.
18. Meyer W, Schwarz R, Neurand K. The skin of domestic mammals as a model for the human skin, with special reference to the domestic pig. Curr Probl Dermatol. 1978;7:39–52.
19. Vardaxis NJ, Brans TA, Boon ME, Kreis RW, Marres LM. Confocal laser scanning microscopy of porcine skin: implications for human wound healing studies. J Anat. 1997;190(Pt 4):601–611.
20. Swindle MM. Surgery, anesthesia and experimental techniques in swine. Ames, Iowa; Iowa State Press: 1998.
21. Kerrigan CL, Zelt RG, Thomson JG, Diano E. The pig as an experimental animal in plastic surgery research for the study of skin flaps, myocutaneous flaps and fasciocutaneous flaps. Lab Anim Sci. 1986;36(4):408–412.
22. Mole JE, Horton HR. Kinetics of papain catalyzed hydrolysis of -N-benzoyl L-arginine-p-nitroanilide. Biochemistry. 1973;12(5):816–822.
23. Blank-Koblenc T, Tor R, Freeman A. Cosolvent effects on gel-entrapped oxidoreductase: the glucose oxidase model. Biotechnol Appl Biochem. 1988;10(1):32–41.



Post new comment

  • Lines and paragraphs break automatically.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Use to create page breaks.

More information about formatting options

Image CAPTCHA
Enter the characters shown in the image.