Abstract
Purpose: :
The Amniotic membrane (AM) is component of extraembryonic membrane, which successully used for ocular surface reconstruction. However, recent emerging data suggests that variation in AM-to-AM biochemical composition may be the cause of less favourable clinical efficacy. The extraembryonic coelom or spongy layer (SL) is the gelatinous, protein-rich layer, which develops between the amnion and the chorion, collectively known as a foetal membrane. This layer often remains association with the AM and is partially but variably removed during preparation of AM for transplantation. Very litle is known about the biochemical composition of the SL. However, considering the embryological formation of the spongy layer and its function as physical boundary between the cellular layers of the vascular chorion and avascular amnion, the potential biochemical composition of the SL is vast. We have demonstrated, that SL contains many potentially beneficial factors, and at considerably higher levels that levels that AM per se, which may explain in part the observed clinical variation. However, the effects of SL on cells growth and differentiation have ye to be established.
Methods: :
SL was isolated from AM, ground under liquid nitrogen and then freeze dried. After reconstitution with assay medium to physiological concentration (the fluidity of AM in vivo), soluble proteins were extracted from SL to produce soluble (sSL) and insoluble fractions (iSL). Fractions Corneal epithelial cells (CEC), keratocyte derived fibroblasts (KDF) and lymphocytes were cultured. The effects on cell proliferation (WST-1), and cytotoxicity by serially diluted SL fractions were measured.
Results: :
At physiological concentration (16mg/ml) iSL killed all cells within a few hours. Serial dilution of iSL (16mg/ml, 8mg/ml, 3.2mg/ml, 0.32mg/ml) reduced speed of death still occured. Stimulation with sSL promoted KDF growth, but killed CEC at all concentrations.
Conclusions: :
SL is a potential but variable deport of factors which affects cells in different ways. Intact SL (iSL) exhibits a cytotoxic effect. On the other hand soluble factors within the SL promote the growth of some cells whilst inhibit the growth of others. Therefore in the current situation where SL is typical ignored during AM preparation for transplantation, resulting in variable and partial SL removal, this may have significant implications for the clinical efficacy of AM.
Keywords: cornea: basic science • cornea: basic science • cornea: epithelium