Human Conjunctival Stem Cells are Predominantly Located in the Medial Canthal and Inferior Forniceal Areas.
OBJECTIVE
The conjunctiva plays a key role in ocular surface defence and maintenance of the tear film. Ex vivo expansion of conjunctival epithelial cells offers potential to reconstruct the ocular surface in cases of severe cicatrising disease, but requires initial biopsies rich in stem cells to ensure long-term success. The distribution of human conjunctival stem cells, however, has not been clearly elucidated.


METHODS
Whole human cadaveric conjunctiva was retrieved and divided into specific areas for comparison. From each donor, all areas from one specimen were cultured for colony-forming efficiency assays and immunocytochemical studies; all areas from the other specimen were fixed and paraffin embedded for immunohistochemical studies. Expression of CK19, p63, and stem cell markers ABCG2, ΔNp63, and Hsp70 were analyzed. Results were correlated to donor age and postmortem retrieval time.


RESULTS
Conjunctiva was retrieved from 13 donors (26 specimens). Colony-forming efficiency and expression of stem cell markers ABCG2, ΔNp63, and Hsp70 in cultures and ABCG2 in fixed tissue were all consistently demonstrated throughout the tissue but with highest levels in the medial canthal and inferior forniceal areas (P < 0.01 for each). Both increasing donor age and longer postmortem retrieval times were associated with significantly lower colony-forming efficiency, stem cell marker expression in cell cultures and ABCG2 expression in fixed tissue.


CONCLUSIONS
Biopsies from the medial canthus and inferior forniceal areas, from younger donors, and with short postmortem retrieval times offer the greatest potential to developing conjunctival stem cell-rich epithelial constructs for transplantation.
Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom.
Rosalind M K
RM
Stewart
Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom.
Carl M
CM
Sheridan
Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom.
Paul S
PS
Hiscott
Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom Department of Biostatistics, University of Liverpool, Liverpool, United Kingdom.
Gabriela
G
Czanner
Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom.
Stephen B
SB
Kaye
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000378:metabolism; D002102:Cadaver; D002478:Cells, Cultured; D003228:Conjunctiva / Q000166:cytology* / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D013234:Stem Cells / Q000378:metabolism; D055815:Young Adult
D015415:Biomarkers
conjunctiva; inferior fornix; medial canthus; progenitor cell; stem cell