SCIENTIFIC REPORT

Characterisation of myofibroblasts in fibrovascular tissues of primary and recurrent pterygia

A Touhami¹, M A Di Pascuale¹, T Kawatika¹, M Del Valle², R H Rosa, Jr³, S Dubovy⁴ and S C G Tseng¹

¹ Ocular Surface Center, Miami, FL, USA
² Laser Institute of Barranquilla, Colombia
³ Department of Ophthalmology, Scott and White Clinic/Texas A&M University System Health Science Center, Temple, TX, USA
⁴ Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL, USA

Correspondence to:
Correspondence to:
Scheffer C G Tseng MD PhD
Ocular Surface Center, 7000 SW 97 Avenue, Suite 213, Miami, FL 33173, USA; stseng{at}ocularsurface.com

Aims: To determine the presence and origin of myofibroblasts in pterygia.

Methods: 86 specimens including head, body, and fibrovascular tissue from 52 primary and 34 recurrent pterygia and five exenterated eyes without pterygia were searched for the origin of myofibroblasts. All tissues were subjected to haematoxylin and eosin staining, immunohistochemistry using antibodies against alpha smooth muscle actin (-SMA), desmin, vimentin, and caldesmon, and transmission electron microscopy (TEM). The phenotype of fibroblasts subcultured in a serum free medium from pterygium fibrovascular tissues was characterised by the above antibodies. Bundles of dense fibrous tissues were noted in 86% of the fibrovascular tissue specimens evaluated. Cells within these bundles were characterised as myofibroblasts based on positive staining to -SMA, but negative to desmin and caldesmon, markers for smooth muscle cells. Interestingly, positive -SMA staining was also found in the periorbital fibroadipose tissue posterior to Tenon’s capsule near the nasal conjunctiva in all exenterated specimens. All first passage fibroblasts expressed vimentin, some were positive to -SMA, but all were negative to desmin or caldesmon. Cells in pterygium fibrovascular tissues showed ultrastructural features of intracytoplasmic bundles of microfilaments, consistent with myofibroblastic differentiation.

Conclusion: These studies collectively demonstrate the presence of contractile myofibroblasts bundle in pterygia and in the periorbital fibroadipose tissue posterior to Tenon’s capsule of exenterated eyes without pterygium.

Abbreviations: AEC, 3-amino-9-ethylcarbazole chromogen; FITC, fluorescein isothiocyanate; -SMA, alpha smooth muscle actin; TEM, transmission electron microscopy

Keywords: pterygium; myofibroblasts; recurrence; proliferation

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