Histologic Features of Transplanted Amniotic Membrane: Implications for Corneal Wound Healing
Received 26 August 2008; received in revised form 19 December 2008; accepted 23 January 2009. published online 18 May 2009.
Purpose
To evaluate the histologic changes occurring in the transplanted amniotic membrane in human eyes.
Design
Observational consecutive case series.
Participants
Seven consecutive patients who underwent amniotic membrane transplantation (AMT) for bullous keratopathy and subsequently had a penetrating keratoplasty (PK).
Methods
Corneal buttons obtained at PK were examined by light and electron microscopy and by immunohistology with antibodies against CD34 (keratocytes), α smooth muscle actin and vimentin (myofibroblasts and fibroblasts respectively). Time from AMT to PK ranged from 2 to 32 months.
Main Outcome Measures
Immunophenotypic characteristics of cells populating transplanted amniotic stroma.
Results
Amniotic tissue was covered with stratified corneal epithelium with well-defined desmosomes and hemidesmosomes. Transformed corneal stroma-derived cells (CSDCs) could be seen migrating from the anterior stroma, through breaks in the Bowman's zone, into connective tissue of the amniotic membrane. Immunohistology showed that the cells populating amniotic stroma were CD34 negative but positive for vimentin and α smooth muscle actin. In 2 samples in which corneal transplants were performed approximately 1 year or more after AMT, some cells in the amniotic stroma showed CD34+ staining. Features of increased metabolic activity and formation of new collagen were seen on electron microscopy. In 2 cases, epithelial cell nests were seen in the amniotic stroma.
Conclusions
The amniotic basement membrane facilitates epithelial cell migration and adhesion. The amniotic stroma supports CSDCs and epithelial cells. Repopulation of the amniotic stroma by CSDCs migrating through breaks in Bowman's zone integrates the amnion with corneal tissue and allows for rebuilding of corneal stroma. Over time, some CSDCs may revert to the resting keratocyte immunophenotype.
Financial Disclosure(s)
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Available online: May 17, 2009.
1Division of Ophthalmology, University of Nottingham, University Hospital, Queens Medical Centre, Nottingham, England
2Research Institute of Ophthalmology, Cairo, Egypt
3Department of Medicine and Ageing Science, Ophthalmic Clinic, University of Chieti-Pescara, Italy
4Division of Histopathology, University of Nottingham, University Hospital, Queens Medical Centre, Nottingham, England
Correspondence: Harminder S. Dua, MD, PhD, FRCS, Division of Ophthalmology and Visual Sciences, B floor, Eye ENT Centre, University Hospital, Queens Medical Centre, Nottingham, NG7 2UH, England
Manuscript no. 2008-1024.
Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
ABSTRACT