Recalcitrant Macular Hole Closure by Autologous Retinal Transplant Using the Peripheral Retina

MANAGEMENT OF AUTOLOGUS RETINAL TRANSPLANT COMPLICATIONS: A CASE SERIES

PURPOSE

To present representative cases of the most common complications associated with an autologous retinal transplant (ART) for macular hole repair.

METHODS

A retrospective, consecutive case series on patients who underwent an ART by a single provider (Tamer H. Mahmoud).

RESULTS

Four cases were included in this review. Each suffered an ART-specific complication, including graft displacement and dislocation, sub-ART perfluoron, and a delayed proliferative vitreoretinopathy-associated retinal detachment.

CONCLUSION

Because more surgeons use ART to treat atypical macular holes, an adequate understanding of surgery-specific complications and techniques to treat those complications is increasingly necessary.

Comparison of three techniques of harvesting full-thickness retinal tissue for large or persistent macular holes

Purpose

To evaluate the success rate of autologous retinal graft (ARG) for the closure of full-thickness macular holes (MHs) and compare the outcomes of three different techniques of harvesting the graft.

Methods

Clinic files of all patients who had undergone ARG for MH using intraocular scissors, membrane loop, or retinal punch to harvest retinal tissue were retrospectively reviewed. All patients were evaluated for MH closure, retinal reattachment, and visual improvement.

Results

Twenty-two eyes of 22 patients were included. ARG was done for 16 eyes (72.7%) with failed, large persistent MH, and six eyes (27.3%) also underwent simultaneous repair of retinal detachment. The basal diameter of MH was 1103.67 ± 310.09 (range 650-1529) μm. Intraocular scissors were used in 10 eyes (45.5%), a membrane loop in five eyes (22.7%), and a retinal punch in seven eyes (31.8%). Silicone oil tamponade was used in seven (31.8%) eyes and gas in 15 (68.1%) eyes. The follow-up ranged from 6 to 18 months. The hole closure rate was 72.7% (16/22). Visual improvement was noted in 18 eyes (81.8%). Retinal reattachment was seen in all eyes. Good graft integration with the surrounding area was seen in 17 eyes (77.3%). Graft retraction was seen in four eyes (18.18%) and graft loss in one eye (4.55%). No significant differences were noted among the three groups.

Conclusion

ARG is successful in closing large, failed MH with and without retinal detachment. A membrane loop and retinal punch are equally useful in harvesting the graft, but scissors are preferable in case the retina is detached. With all three techniques, integration of the graft with the surrounding tissue can be achieved.

Autologous Retinal Transplant for Macular Hole

We aim to review scientific literature concerning published studies on autologous retinal transplantation to treat macular hole patients. The following databases were searched: Medline and Medline Non-Indexed Items, Embase (1990–2020), Ovid Medline® (1990 to November 2020), Embase (1990 to November 2020), Ovid Medline® and Epub Ahead of Print, in-Process and Web of Science (all years). Search keywords included “autologous”, “retinal transplant”, “autologous neurosensory retinal free flap” “transplantation”, “macular hole”, and “macular hole surgery”. Eighteen case series and single case reports were reviewed.

Preoperative and final best-corrected visual acuity, microperimetry and multifocal electroretinogram findings, macular hole closure rate, preoperative and postoperative ellipsoid zone, and external limiting membrane defects were obtained and analyzed. Indications of autologous retinal transplantation for macular hole surgery included refractory macular holes, conventional techniques, and large macular holes. The number of cases included in the different case series ranged from 2 to 130 cases, and prior macular hole surgeries of the patients ranged from 0 to 3. Overall, the published case series of autologous retinal transplants have reported a macular hole closure rate of 66.7 to 100%, as well as a significant improvement in best-corrected visual acuity. The most frequently reported complications included considerable intraoperative bleeding and postoperative dislocation of the graft. The presence of functionality in the graft area has also been documented by microperimetry and multifocal electroretinogram.

In conclusion, the autologous retinal transplantation technique for macular hole patients has emerged as another surgical option, with a high macular hole closure rate and visual improvement.

Retinal Stem/Progenitor Cells Derived From Adult Müller Glia for the Treatment of Retinal Degeneration

Over the past two decades, progress in our understanding of glial function has been revolutionary. Within the retina, a subset of glial cells termed the “Müller glia (MG),” have been demonstrated to play key roles in retinal homeostasis, structure and metabolism. Additionally, MG have also been shown to possess the regenerative capacity that varies across species. In teleost fish, MG respond to injury by reprogramming into stem-like cells capable of regenerating lost tissue. The expression of stem/progenitor cell markers has been demonstrated broadly in mammalian MG, including human MG, but their in vivo regenerative capacity appears evolutionarily limited. Advances in stem cell therapy have progressively elucidated critical mechanisms underlying innate MG reprogramming in teleost fish, which have shown promising results when applied to rodents. Furthermore, when cultured ex vivo, MG from mammals can differentiate into several retina cell types. In this review, we will explore the reparative and regenerative potential of MG in cellular therapy approaches, and outline our current understanding of embryonic retinal development, the stem-cell potential of MG in adult vertebrate retina (including human), and microenvironmental cues that guide MG reprogramming.

SURGICAL RETINAL EXPLANTS AS A SOURCE OF RETINAL PROGENITOR CELLS

PURPOSE

To describe the novel observation of spontaneously migrating retinal cells from living donor surgical retinal explants that express progenitor cell markers in the absence of exogenous growth factors.

METHODS

Surgical retinal explants were harvested from 5 consecutive patients undergoing 23 G pars plana vitrectomy for the management of rhegmatogenous detachment. During surgery, equatorial flap tears were trimmed with the vitreous cutter and aspirated. Excised tissue was then regurgitated into a syringe containing balanced salt solution and immediately transferred to tissue culture. Migrating cells subsequently underwent immunohistochemical staining and their characteristics were compared with those of a spontaneously immortalized Müller stem cell line.

RESULTS

Spontaneously migrating cells were observed from samples taken from all 5 patients from Day 2 to 10 after transfer to culture. These cells were found to express embryonic cell markers, including paired box 6 (Pax6), sex-determining region Y-box 2 (Sox-2), nestin, cone-rod homeobox, and cyclin-dependent kinase inhibitor 1B (p27Kip1) as well as proteins consistent with early or retained differentiation down the Müller cell lineage, including glial fibrillary acidic protein and glutamine synthetase.

CONCLUSION

After injury, the human equatorial retina is capable of spontaneously producing cells that demonstrate migration and that express progenitor cell markers. In addition, these cells express proteins consistent with Müller cell lineage. These initial observations support the assertion that the human retina may possess the potential for regeneration and that surgical retinal explants could also act as a ready source of retinal progenitor cells.