A Closer Look At Amniotic Membrane Allografts For Wounds

Recently my organization, the American Association for Women Podiatrists, hosted a scientific conference in San Diego. One of the speakers was Marie Williams, DPM, who discussed the advances in regenerative medicine in wound care. Listening to her presentation left me with more questions. Here is what I found. 

The Centers for Disease Control and Prevention (CDC) has projected that by 2050, as many as one out of three U.S. adults could have diabetes.¹ As many as 25 percent of patients with diabetes will develop an ulceration in their lifetime.¹ The goal is to heal these wounds in the fastest manner possible in order to prevent infection, ulceration and amputation. If an ulcer does not respond appropriately to standard care at four weeks, then it requires re-evaluation of the current treatment plan and one should consider an advanced modality.² Amniotic membrane allograft is a more recent advanced modality in wound care.

Since the early 20th century, human amniotic membrane allografts have been in widespread use in a variety of applications including burn care, dentistry, ophthalmic, ear, nose and throat, and spine surgery. Human amniotic membrane products have become a widely accepted form of treatment in ophthalmic surgery, including corneal ulceration, covering of defects in large conjunctival lesions and acute chemical burns of the eye. Recently, physicians have effectively applied amniotic membrane products to help facilitate healing in chronic cutaneous wounds, including diabetic, venous, arterial and decubitus ulcers.^3-7

The amniotic membrane derives from the inner layer of the placenta and is composed of conjoined amnion and chorion membranes. The amnion is in contact with the amniotic fluid/fetus and the chorion is in contact with the maternal side of the placenta. Both layers are non-immunogenic. Human amniotic membrane forms the lining of the fetal environment during gestation, separating the developing fetus from the mother in utero.

The material used for surgical wound allografts is isolated from the membranous sac surrounding the infant to the point where it adjoins the placenta at the chorionic plate. The amniotic membrane is composed principally of structural collagen, extracellular matrix, biologically active cells and a large number of important regenerative molecules. Collagen types IV, V and VII make up the extracellular matrix, and are substrates that are important for the integrity of the membrane and ingrowth of cells. The membrane also includes proteins such as fibronectin, proteoglycans, glycosaminoglycans and laminins, epidermal growth factor (EGF), transforming growth factor (TGF), fibroblast growth factor and platelet-derived growth factors. Amniotic membrane has both matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs).

Current Insights On The Benefits Of Amniotic Membrane

There are a variety of benefits with the use of amniotic membrane products for wound healing.^4,6

• The extracellular matrix scaffold aids in the organization of the body’s wound healing process

• Amniotic membrane promotes increased healing and enhancement of the wound healing process.

• Amniotic membrane is non-immunogenic, has antibacterial properties, reduces inflammation and reduces scar tissue.

• The growth factors accelerate healing by stimulating angiogenesis and granulation tissue formation.

• Amniotic membrane reduces pain at the site of application and provides a natural biological barrier.

• Amniotic membrane contains a number of essential growth factors and cytokines.

• Amniotic membrane provides a natural human tissue scaffold, which acts as a medium that enables cell proliferation and differentiation.

Manufacturers supply human amniotic grafts dehydrated at room temperature or frozen. Amniotic membrane wound allografts do not need suturing and clinicians can use steri-strip adhesives to hold them in place. Cover the graft with a non-adherent contact and do not disturb it for one to two weeks. The secondary dressing environment should be moist and one should use an appropriate moisture management dressing for the wound type. Amniotic membrane allograft will incorporate into the wound bed within one to two weeks. According to the research, you should see an improvement in the wound margins and depth within two to three weeks.⁴ Anecdotally, wound margins can typically reduce by 40 to 50 percent within three to four weeks with amniotic membrane use in typical wounds in comparison to more than four weeks of standard therapy.

In Conclusion

There are currently several companies on the market manufacturing ammonic allografts for wounds and it can be difficult to understand the differences in each. After this research, I feel I have a better understanding of these products and will be using amniotic membrane soon. Additional research and characterization of these products are necessary. I would like to hear everyone else’s experience on their use of these products. 

References

1. Centers for Disease Control and Prevention. Available at https://www.cdc.gov/chronicdisease/resources/publications/aag/ddt.htm .

2. Sheehan P, Jones P, Giurini JM, et al. Percent change in wound area of diabetic foot ulcers over a four-week period is a robust predictor of complete healing in a 12-week prospective trial. Plast Reconstr Surg. 2006; 117(7 Suppl):239S-244S.

3. Koob TJ, Lim JJ, Massee M, et al. Properties of dehydrated human amnion/chorion composite grafts: Implications for wound repair and soft tissue regeneration. J Biomed Mater Res B: Appl Biomater. 2014; 102(6):1353-62.

4. Fetterolf DE, Snyder RJ. Scientific and clinical support for the use of dehydrated amniotic membrane in wound management. Wounds. 2012;24(10):299-307.

5. Wong VW, Gurtner GC, Longak MT, et al. Wound healing: a paradigm for regeneration. Mayo Clinic Proc. 2013; 88(9):1022-31.

6. Shum K, Rogers LC. Amniotic membrane: does it have promise for diabetic foot ulcers? Podiatry Today. 2013; 26(6):14-16. 

7. Zelen CM, Serena T, Fetterolf D. Human amniotic membrane in the treatment of non-healing diabetic foot ulcers: a randomized controlled trial. Abstract presentation, Clinical Symposium on Advances in Skin and Wound Care, Orlando, FL, 2012.