Combined Therapy Using Human Corneal Stromal Stem Cells and Quiescent Keratocytes to Prevent Corneal Scarring after Injury

Abstract

Corneal blindness due to scarring is conventionally treated by corneal transplantation, but the shortage of donor materials has been a major issue affecting the global success of treatment. Pre-clinical and clinical studies have shown that cell-based therapies using either corneal stromal stem cells (CSSC) or corneal stromal keratocytes (CSK) suppress corneal scarring at lower levels. Further treatments or strategies are required to improve the treatment efficacy. This study examined a combined cell-based treatment using CSSC and CSK in a mouse model of anterior stromal injury. We hypothesize that the immuno-regulatory nature of CSSC is effective to control tissue inflammation and delay the onset of fibrosis, and a subsequent intrastromal CSK treatment deposited collagens and stromal specific proteoglycans to recover a native stromal matrix. Using optimized cell doses, our results showed that the effect of CSSC treatment for suppressing corneal opacities was augmented by an additional intrastromal CSK injection, resulting in better corneal clarity. These in vivo effects were substantiated by a further downregulated expression of stromal fibrosis genes and the restoration of stromal fibrillar organization and regularity. Hence, a combined treatment of CSSC and CSK could achieve a higher clinical efficacy and restore corneal transparency, when compared to a single CSSC treatment.

Biomimetic Corneal Stroma for Scarless Corneal Wound Healing via Structural Restoration and Microenvironment Modulation

“…Recently, Jhanji et al reported an approach to combine keratocytes with corneal stromal stem cells (CSSCs) to reduce scarring. [48] This combined therapy appears to replenish corneal transparency-related proteoglycans via keratocytes and control inflammation via CSSCs, thus achieving higher efficacy than a single treatment. Since the combined therapy involves different cell types and depends on the ratio between them, it is more complex to manipulate, which is unfavorable for the repeatability and consistency of the procedures.…”

Regenerative Therapy for Corneal Scarring Disorders

“…At the stromal periphery (anterior limbal stroma), the existence of corneal stromal stem cells (CSSCs) represents an adult progenitor population for CSK. Although there is a lack of in situ evidence showing their differentiation to produce CSK inside CSt, different pre-clinical studies have indicated their therapeutic potency to remodel CSt after injury, resulting in stromal regeneration and a recovery of regular lamellar pattern [ 7 , 8 , 9 ].…”

“…Native CSKs are difficult to expand ex vivo, as they transit to fibroblasts when propagated with serum and growth factors in culture [ 18 , 71 ]. Our laboratory developed a robust method to expand bona fide CSKs ( Figure 4 A) [ 15 ], which specifically (1) produce and deposit stromal collagens, particularly type I collagen; (2) express stromal proteoglycans (such as keratocan, lumican, and decorin) and stromal crystallins (transketolase, aldehyde dehydrogenase 1A1 and 3A1); and (3) become quiescent in a serum-deprived condition and express CD34 and integrins on the cell surface for intercellular communication [ 9 , 15 , 72 ]. Using in vivo mouse and rat corneal stromal injury models (induced by excimer laser-mediated irregular photorefractive keratectomy and mechanical ablation by high-speed Algerbrush burring, respectively), CSKs were intrastromally injected to corneas with pre-existing early corneal haze and opacities.…”

Recent advances in cell-based regenerative therapies for corneal disease

“…Both groups that received ADASC demonstrated improvement in paracentral scars. Meanwhile, other candidates for cell replacement are being explored, such as corneal stromal SC which have been shown to control inflammation and fibrosis [28,29]; stromal keratocytes which demonstrated ability to recover the native stromal matrix [30]; or a combination of both [31]. Similarly, additional tissue engineering approaches are exploring different scaffolds [32][33][34].…”