Amniotic Membrane: An Innovative Material for Repair and Regeneration in Oral and Maxillofacial region- A Review

Amniotic membrane is the inner most lining of the human placenta that is normally discarded after parturition. The membrane has numerous growth factors, proteins and stem cell reserves that help in accelerating wound healing with regeneration of the lost tissues. With improvements in the processing and storage technologies, amniotic membrane has found application in various fields of surgery. Recently, this tissue has found application in the field of maxillofacial surgery, because of its inherent wound-modulating properties. This review paper discusses the structure, properties, mechanisms and the applications of this neglected tissue that makes it a potential material for regeneration especially in the field of oral and maxillofacial surgery. KeywordsAmniotic membrane, growth factors, stem cells, maxillofacial surgery. INTRODUCTION Regenerative medicinal therapy has emerged as a powerful tool to generate biological substitutes and repair damaged tissues, by either transplanting exogenous or stimulating endogenous stem cells with highly proliferative, differentiability, to restore proper function and provide better aesthetics. Mesenchymal stem cells (MSC) are one of the major cell populations, to mediate regeneration due to their multipotential properties, They can be obtained from various tissues such as bone marrow, periosteum, peripheral blood, adipose tissues and skin. MSC obtained from these tissues have a few limitations, relatively invasive procedure and poor quality of cells if taken from elderly or medically compromised patients. Therefore newer developments in tissue engineering are focused on alternate sources of MSC, to provide adequate amount of stem cells with minimal patient morbidity. Amniotic membrane of the human placenta is a rich source of stem cells and studies have shown that human amniotic mesenchymal cells (hAMSC) are non tumorigenic, have anti-inflammatory and low immunogenicity effects and are capable of differentiating into three forms of germ layers. Advantages of hAMSC over autogenously derived stem cells are no morbidity in its procurement procedures, unlimited amount available and isolation of hAMSC does not sacrifice the embryo, as in the case of embryonic stem cells, thus no legal or ethical issues arise. Based on these factors amniotic membrane (AM), can be preserved and used as a source of stem cells in various tissue regenerative modalities. Here we present an overview of its inherent structure, properties, processing methods and clinical applications in maxillofacial surgery. The review was based on 3 electronic databases (MEDLINE, EMBASE, Cochrane) for articles published from 1910 to 2015. In addition, selected journals were searched by hand for relevant articles, on human amniotic membrane and its application in maxillofacial surgery. HistoryPlacental tissues are being used, for the treatment of wounds and reconstructive procedures since the early 20 century. Davis in 1910, first reported the use of fetal membrane as skin substitutes for treating open wounds. later it was advocated in the management of conjunctival defects, burns and skin ulcers. But due to lack of proper sterilization protocols and storage procedures, its use was diminished. In 1965, Dino et al demonstrated how to separate, sterilize and store AM. In maxillofacial surgery, Lawson first used AM with PMMC flap for closure of oral defects in 1985. Lai et al, in 1995 used single layer of amnion in treatment of OSMF. AM was also used in vestibuloplasty, oronasal/oroantral fistulas and as an