Characterization of equine hyalocytes: their immunohistochemical properties, morphologies and distribution

Morphological, Immunohistochemical, and Ultrastructural Studies of the Donkey's Eye with Special Reference to the AFGF and ACE Expression

The donkey is mainly used as a working animal for riding and pack transport, as well as for dairy and meat production. Eye afflictions are common in donkeys, thus requiring a detailed study. A few studies had focused on the donkey's eye, and most of them had considered it, merely, a horse's eye. This study aimed to investigate the anatomy, histology, ultrastructure, and immunohistochemical features of the donkey's eye. The results were recorded and compared to those of horses in certain dimensions. Unlike horses, the donkey's eye is more circular in the contour of the cornea, has smaller lenticular thickness, and has longer anterior and vitreous chambers. Positive immunoreactivity to acidic fibroblast growth factor in the basal cell layers of the cornea was observed, indicating their role in cell differentiation and the renewal of the epithelium. Moreover, the corneal keratocytes expressed angiotensin-converting enzyme, which plays a role in corneal homeostasis and wound healing. Additionally, telocytes, hyalocytes, and other immune cells were observed within the iris and ciliary processes. Hence, this work is an updated detailed study of the morphology and ultrastructure of the donkey's eye and reveals some similarities and dissimilarities to the horse's eyes, which should be considered in clinical practice.

In vitro generation of primary cultures of human hyalocytes

Purpose

A growing number of studies on animal models have demonstrated that some ocular diseases are the result of the interaction between hyalocytes and the ocular inflammatory setting. Endogenous and exogenous substances might alter the structure and behavior of hyalocytes that can contribute to the pathogenesis of some ocular diseases. Obtaining primary cultures of human hyalocytes could help understand the role of these cells in response to different treatments.

Methods

Hyalocytes were isolated from eyes of 54 patient volunteers subjected to vitrectomy for different clinical reasons. By testing different matrices and growth media, we reproducibly generated primary cultures of hyalocytes that we characterized morphologically and biologically, basally and upon treatment with several agents (basic fibroblast growth factor (bFGF), transforming growth factor beta 1 (TGF-β), platelet-derived growth factor subunit-BB (PDGF-BB), ascorbic acid, dexamethasone, and hydrogen peroxide).

Results

We were able to generate primary cultures from vitreous human samples, growing the cells on collagen-coated plates in Iscove's modified Dulbecco's medium supplemented with 10% fetal bovine serum; primary cells expressed the hyalocyte markers. Specific cytoskeletal modifications were observed upon treatment with bFGF, TGF-β, PDGF-BB, ascorbic acid, dexamethasone, and hydrogen peroxide. Only bFGF was able to promote cell growth and hyaluronic acid production.

Conclusions

We describe for the first time the generation and the characterization of primary cultures of human hyalocytes from living donors. Although human hyalocytes share some characteristics with animal hyalocytes, human hyalocytes have their own features typical of the species, confirming how important human experimental models are for investigating human pathologies and their treatments.

[Hyalocytes of the vitreous body and their role in ophthalmic pathology]

Hyalocytes of the vitreous body are variety of tissue macrophages that exercise various functions - from ensuring the synthesis of extracellular matrix components and modulating the immune response in the vitreous body to participating in different stages of inflammatory processes. Some aspects of the biology of hyalocytes remain poorly understood and controversial. However, the vitreous cells are starting to be considered a potential point of application in the treatment of diseases of the vitreous body and the retina.