Purpose:
To evaluate the ability of human Adipose-derived stem cells (ASCs) to regenerate corneal stroma.
Methods:
This study consisted of two phases. In the first set of experiments, we investigated the ability of ASCs to proliferate on three-dimensional culture media made of modified hyaluronic acid. (HyStem-HPTM, ExtracelTM, Hystem-CTM, Glycosan Biosystems Inc. Salt Lake City, UT). In the second phase, regeneration of corneal stroma by ASCs was assessed in rabbit corneas. Nine white New Zealand rabbits underwent two types of surgical procedures. Lasik flaps were made in 6 rabbits using a CB-Moria microkeratome (Moria Inc. Doylestown, PA), and manual stromal pockets were created in three others. 300,000 cells/100 µl labeled by CM-Dil fluorescence in conjunction with four different types of scaffolds (HyStem-HPTM, ExtracelTM, Hystem-CTM from Glycosan Biosystems Inc. Salt Lake City, UT, and HealonTM from Abbott Medical Optics Inc. Santa Ana, CA) were introduced into the stromal pockets and under the stromal flaps. After 10 weeks, viability of stem cells and expression of human aldehyde-3-dehydrogenase (ALDH) and cornea specific proteoglycan keratocan and collagen 1 and 6 were assessed.
Results:
The in vitro study showed HyStem-HPTM to be superior to ExtracelTM and Hystem-CTMfor culturing ASCs, with the highest yield of cells after 10 days. (1x10^6 cells compared to ExtracelTM (5.2x10^5 cells) and Hystem-CTM(5.6x10^5 cells)). Furthermore, the HyStem-HPTM culture media produced the most desirable ASC morphology. ASCs were identified in the rabbit corneal stromas at 10 weeks post inoculation with all four types of scaffolds. Modified hyaluronic acid scaffolds (HyStem-HPTM, ExtracelTM, Hystem-CTM) produced better survival and cell morphology relative to hyaluronic acid (HealonTM). Immunostaining of keratocan, ALDH and collagen 1, 6 confirmed differentiation of stem cells to keratocytes. Figure 1
Conclusions:
Human ASCs in tandem with a 3 dimensional hyaluronic acid scaffold are capable of differentiating into human corneal keratocytes in vivo. This could represent a novel method for bioengineering corneal stroma.
Keywords: cornea: stroma and keratocytes