The long term outcome of limbal allografts: the search for surviving cells

Abstract

Background/aims-Limbal allotransplantation is increasingly being used for ocular surface repair in patients with limbal stem cell dysfunction. However, it is uncertain whether donor cells survive long term on the ocular surface and whether patients maintain the early benefits of the procedure. The aims of this study were to investigate the long term outcome of clinical limbal allografts and to correlate outcome with donor cell survival. Methods-Five patients who had undergone allotransplantation-four keratolimbal allografts and one tarsoconjunctival allograft-from 3-5 years previously, and for whom residual frozen donor ocular tissue was available, were reviewed. Survival of donor cells lifted from the recipient ocular surface by impression cytology was investigated by DNA fingerprinting using primers detecting variable nucleotide tandem repeat sequences. Recipient buccal cells and scleral samples from the remnant donor eye were used to genotype recipients and donors, respectively. Polymerase chain reaction products were sized by Genescan analysis. Results-An objective long term benefit from the procedure (improved Snellen acuity, reduced frequency of epithelial defects, reduced vascularisation, and scarring) was recorded for four patients. Some subjective benefit was also reported. However, in no instances were donor cells recovered from the ocular surface at 3-5 years post-graft. Initial experiments to examine sensitivity indicated that any surviving donor cells must have constituted less than 2.5% of cells sampled. Conclusion-Limbal stem cell allotransplantation can provide long term benefits, as measured by objective criteria. However, such benefits do not necessarily correlate with survival of measurable numbers of donor cells on the ocular surface. (Br J Ophthalmol 2001;85:604-609)

Assessment of limbus and central cornea in patients with keratolimbal allograft transplantation using in vivo laser scanning confocal microscopy: an observational study

“…Palisades of Vogt might be vital in maintaining the normal state and function of LSC [20][21][22]. The morphology of palisades of Vogt in survived grafts were similar to that in normal humans observed by a previous study [12], with a wavy epithelium-stromal boundary or alternating epithelium-stromal cords, hyperreflective basal epithelial cells, and [23]. Others were able to detect donor cells in a majority of the recipients up to 3.5 years after transplant [24,25].…”

Effect of Immunosuppression on Survival of Allograft Limbal Stem Cells

“…11 In some clinically successful limbal allografts without donor-derived cells, it may be possible that donor-derived cells remained in the basal epithelium and thus were not sampled. 10 Another possible explanation is that immunosuppression does indeed enhance the survival of limbal stem cells, but donor-derived cells coming from transplanted limbal stem cells are destroyed by the rejection reaction on the recipient corneal surface. Further studies are needed to find ways to enhance the survival of both stem and donor-derived cells.…”

“…No donor cells could be detected on the ocular surface by DNA fingerprinting analysis. 10 Shimazaki et al 11 followed patients who had received ring-shaped limbal allografts with topical and systemic immunosuppression. Using fluorescent in situ hybridization and restriction fragment length polymorphism analyses, they demonstrated longterm survival of donor cells on the corneal surface after transplantation in 7 of 10 eyes.…”

“…The presence of donorderived cells on the recipient ocular surface is used as evidence for estimating the effect of a limbal allograft. [9][10][11][12] However, even after some clinically successful limbal allografts, these cells are difficult to find. 10,12 To further evaluate the efficacy of an immunosuppressant, an animal model is needed to facilitate assessment of the survival of limbal allograft stem cells.…”

Surgical rehabilitation following severe ocular burns

“…Although it is likely that transplanted stem cells in an autograft will survive indefinitely, evidence from studies of conjunctival limbal allograft transplantation or transplantation of in vitro amplified allogeneic limbal stem cells indicates a survival of up to 9 months, whereas a successful clinical outcome may persist. 34,52,41,53 Finally, an important implication of in vitro amplification techniques are the infrastructure and staffing costs that make it an expensive and time-consuming procedure that is subject to tight regulation. 54 Despite progress in this field, not all severely damaged eyes are suitable for ocular surface reconstruction, and for these patients synthetic corneal implants (eg, keratoprosthesis, 55 osteo-odontokeratoprosthesis 56 ) continues to be an option.…”