Amniotic Membrane Transplantation in Treatment of Persistent Corneal Ulceration after Severe Chemical and Thermal Eye Injuries

Impact of adjuvant amniotic membrane transplantation in infectious ulcerative keratitis

PURPOSE

To evaluate the effectiveness of cryopreserved human amniotic membrane transplantation (hAMT) in patients with infectious ulcerative keratitis.

METHODS

A retrospective cohort study based on medical records of patients who underwent hAMT procedure over a 2-year period (2020-2021) was conducted at Ege University Hospital, Turkey. Cryopreserved hAM was used. Best corrected visual acuity (BCVA) was measured with the Snellen chart. Detailed ophthalmological examination was performed at all visits. Treatment success was defined as complete healing including disappearance of corneal infiltrates, epithelial defect closure, reduction in anterior segment reaction.

RESULTS

A total of 13 eyes of 12 patients were diagnosed with ulcerative keratitis between 2020 and 2021. hAMT was performed in severe keratitis patients in which corneal infiltrates extending to middle to deep stromal and patients with neurotrophic component, in other words, having trouble for wound healing. The mean age was 60.9 ± 18.7 years, and 66.6% of the patients were male. Average ulcer horizontal diameter was 9.7 ± 2.8 mm. A single-layer human amniotic membrane (hAM) was transplanted 92.3% of eyes. Overlay technique was used in all patients for hAMT. The mean residence time of the amniotic membrane on the ocular surface was 14.1 ± 10.2 days. The mean time from the first presentation to the hAM transplantation was 9.7 ± 6.8 days. The average hospitalization time of all patients was 15 ± 12.1 days, pre-hAMT was 10.2 ± 7.3 days and post-hAMT was 4.8 ± 9.1 days. The mean follow-up time was 3 months. Recovery response was positive in 76.9%. Average healing time was 32.1 ± 14.04 days.

CONCLUSIONS

hAMT was effective in the treatment of infectious ulcerative keratitis by accelerating and supporting wound healing. Performing hAM transplantation at the early stages of the disease and prolonged residence of membrane on the ocular surface increase the success of the treatment and moreover shortens hospitalization time.

OUP accepted manuscript

The corneal epithelium serves to protect the underlying cornea from the external environment and is essential for corneal transparency and optimal visual function. Regeneration of this epithelium is dependent on a population of stem cells residing in the basal layer of the limbus, the junction between the cornea and the sclera. The limbus provides the limbal epithelial stem cells (LESCs) with an optimal microenvironment, the limbal niche, which strictly regulates their proliferation and differentiation. Disturbances to the LESCs and/or their niche can lead to the pathologic condition known as limbal stem cell deficiency (LSCD) whereby the corneal epithelium is not generated effectively. This has deleterious effects on the corneal and visual function, due to impaired healing and secondary corneal opacification. In this concise review, we summarize the characteristics of LESCs and their niche, and present the current and future perspectives in the management of LSCD with an emphasis on restoring the function of the limbal niche.

Case Series Describing the Use of Low-Temperature Vacuum-Dehydrated Amnion (Omnigen) for the Treatment of Corneal Ulcers in Cats and Dogs: 46 Cases (2016-2017)

Amniotic membrane is widely used in the treatment of ocular surface disorders in human and veterinary patients. Preservation and storage of amnion has proven challenging, prompting the development of new preservation techniques. Omnigen, a novel low-temperature vacuum-dehydrated amnion, is reported to possess enhanced structural properties and biochemical stability in vitro, but its clinical use in veterinary patients is not well described. This study aims to document and describe the varied use of Omnigen for the surgical treatment of corneal ulceration in cats and dogs. A total of 45 patients (46 eyes) were recruited from the clinical record system of the Royal Veterinary College (London) between January 2016 and December 2017. Brachycephalic breeds were over-represented (37/45; 82.2%). Omnigen was used as a standalone graft in 5/46 (10.9%) eyes, as a supplementary graft in 29/46 (63.0%) eyes and as a patch in 12/46 (26.1%) eyes. Graft failure occurred in 10/46 eyes (21.7%). At final examination 43/46 eyes (93.5%) had healed and 31/33 eyes (93.9%) were visual. This study demonstrates the successful use of Omnigen for the surgical treatment of corneal ulceration in cats and dogs. Further studies are needed to clarify its properties and benefits in the clinical field.

Therapeutic Potential of Human Amniotic Epithelial Cells on Injuries and Disorders in the Central Nervous System

Despite recent advances in neurosurgery and pharmaceuticals, contemporary treatments are ineffective in restoring lost neurological functions in patients with injuries and disorders of the central nervous system (CNS). Therefore, novel and effective therapies are urgently needed. Recent studies have indicated that stem cells, including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and mesenchymal stem cells (MSCs), could repair/replace damaged or degenerative neurons and improve functional recovery in both preclinical and clinical trials. However, there are many unanswered questions and unsolved issues regarding stem cell therapy in terms of potency, stability, oncogenicity, immune response, cell sources, and ethics. Currently, human amniotic epithelial cells (hAECs) derived from the amnion exhibit considerable advantages over other stem cells and have drawn much attention from researchers. hAECs are readily available, pose no ethical concerns, and have little risk of tumorigenicity and immunogenicity. Mounting evidence has shown that hAECs can promote neural cell survival and regeneration, repair affected neurons, and reestablish damaged neural connections. It is suggested that hAECs may be the most promising candidate for cell-based therapy of neurological diseases. In this review, we mainly focus on recent advances and potential applications of hAECs for treating various CNS injuries and neurodegenerative disorders. We also discuss current hurdles and challenges regarding hAEC therapies.

Effectiveness of Cryopreserved Amniotic Membrane Transplantation in Corneal Ulceration: A Meta-Analysis

PURPOSE

To evaluate the effectiveness of cryopreserved amniotic membrane transplantation (AMT) in corneal ulceration.

METHODS

The following electronic databases were searched: PubMed, EMBASE, and Cochrane Library. We evaluated the corneal epithelium healing rate (CEHR) and vision improvement rate (VIR) after AMT in the treatment of corneal ulceration. We analyzed the differences in the CEHR and VIR between the 2 groups of infective and noninfective corneal ulcerations. Subgroup analysis for the CEHR and VIR was performed based on the surgical methods. There were 3 subgroups: single-layered inlay, multilayered inlay, and sandwich (SAN). The differences were tested by referring to the Cochrane Handbook. Pooled estimates were determined with STATA software, version 15.

RESULTS

Eighteen eligible studies reporting the outcomes in 390 eyes of 385 patients were included. The results of the meta-analysis showed that the pooled CEHR was 97% (I = 37.9%, 95% confidence interval: 0.94-0.99, P = 0.089). The pooled VIR was 53% (I = 68.1%, 95% confidence interval: 0.42-0.65, P < 0.001). There were no significant differences in either the CEHR or the VIR between the 2 groups of infective and noninfective corneal ulcerations. Among the 3 subgroups of single-layered inlay, multilayered inlay, and SAN, the differences in both CEHR and VIR were statistically significant.

CONCLUSIONS

Consistent with many published reports, this meta-analysis also concluded that AMT was effective in the treatment of corneal ulceration. The curative effect of AMT was not different between the infective and noninfective corneal ulcerations. The differences in both CEHR and VIR were statistically significant among the subgroups.

Efficacy of self-retained cryopreserved amniotic membrane for treatment of neuropathic corneal pain

PURPOSE

Treatment of neuropathic corneal pain (NCP) remains intricate, and involves a long-term combined multistep approach. The self-retained cryopreserved amniotic membrane (PROKERA®, Bio-Tissue, Miami,FL) has been utilized for multiple ocular surface disorders. We evaluate the efficacy, safety, and tolerability of ProKera® Slim [PKS] and ProKera® Clear [PKC] in the treatment of NCP.

METHODS

Retrospective case series of 9 patients who received PKS/PKC for the acute treatment of NCP. Patient demographics, prior therapies, clinical examination, duration of PKS/PKC retention, changes in pain severity, corneal subbasal nerve density and morphology by in vivo confocal microscopy (IVCM; HRT3/RCM, Heidelberg Engineering, Heidelberg, Germany), and adverse events were recorded.

RESULTS

PKS/PKC were placed in 10 eyes of 9 patients. Pain severity improved by 72.5 ± 8.4% (from 6.3 ± 0.8 to 1.9 ± 0.6, scale 1-10, p = 0.0003) after retention for 6.4 ± 1.1 days. Despite shorter retention for 4.0 ± 0.7 days in patients with ring dysesthesia (4 eyes) or premature implant disengagement (2 eyes), pain severity still improved by 63.1 ± 12.5% (from 6.8 ± 1.0 to 2.4 ± 0.9, p = 0.009). During a follow-up of 9.3 ± 0.8 months, two patients reported recurrence of pain after 2.3 and 9.6 months respectively, treated effectively with additional PKS/PKC. IVCM showed a 36.6 ± 17.6% increase in total nerve density, from 17,700.9 ± 1315.7 to 21,891.3 ± 2040.5 μm/mm2 (p = 0.047), while the fellow PKS/PKC-untreated eyes did not show a significant interval change. Main nerve trunk and branch nerve densities were not statistically different. Dendritiform cell density decreased from 46.0 ± 8.2 to 32.0 ± 6.0 cells/mm2 (p = 0.01).

CONCLUSIONS

PKS/PKC provide a safe and effective treatment approach to achieve sustained pain control in patients with NCP.

Recurrent cubital tunnel syndrome treated with revision neurolysis and amniotic membrane nerve wrapping

BACKGROUND

Perineural scarring of the ulnar nerve is a predominant cause of symptom recurrence after surgical treatment for primary cubital tunnel syndrome (CuTS). We report our preliminary experience in revision ulnar nerve decompression and nerve wrapping with an amniotic membrane allograft adhesion barrier for treatment of recurrent CuTS.

METHODS

We performed a retrospective review with prospective follow-up of patients with recurrent CuTS who were treated with revision neurolysis with amniotic membrane nerve wrapping. Preoperative elbow motion, grip and pinch strengths, pain level on the visual analog scale level, and the 11-item version of the Disabilities of the Arm, Shoulder and Hand functional outcome score were compared with postoperative values using paired t testing. Symptom characteristics, physical examination findings, complications, and level of satisfaction were also obtained.

RESULTS

Eight patients (mean age, 47.5 years) who had undergone at least 2 prior ulnar nerve operations satisfied study inclusion. At mean postoperative follow-up of 30 months, significant improvements were noted across all patients in visual analog scale pain levels (-3.5 vs. preoperatively; P < .0001), 11-item version of the Disabilities of the Arm, Shoulder and Hand scores (-30 vs. preoperatively; P < .0001), and grip strength (+25 pounds vs. preoperatively; P < .0001). Pinch strength and elbow motion were also significantly improved for those patients with comparative preoperative data available. All patients expressed subjective satisfaction with their results. No adverse reactions or complications occurred in any patients.

CONCLUSIONS

Ulnar nerve wrapping with amniotic membrane allograft, when combined with revision neurolysis, was a safe and subjectively effective treatment for patients with debilitating recurrent CuTS.

Total ocular surface amniotic membrane transplantation for paraquat-induced ocular surface injury

OBJECTIVE

To evaluate the therapeutic efficacy of modified amniotic membrane transplantation (MAMT) for paraquat-induced ocular surface injury.

DESIGN

Retrospective case series.

PARTICIPANTS

Thirty patients (30 eyes) with paraquat-induced ocular surface injury.

METHODS

Among the patients, 8 underwent MAMT, 14 received conventional amniotic membrane transplantation (AMT), and 8 were treated with simple drug therapy (DT). Features related to the damage, corneal epithelial defect closure time, visual acuity, stromal haze, and complications were recorded.

RESULTS

In the MAMT and AMT groups, visual acuity in all eyes recovered to the preinjury level; in the DT group, visual acuity in 3 eyes (37.5%) recovered to the preinjury level. The mean corneal epithelial defect closure time was 7.6 ± 2.7 days in the MAMT group, 9.8 ± 3.6 days in the AMT group, and 18.2 ± 5.2 days in the DT group (p < 0.05). There was a significant difference in the symblepharon rate after treatment among the 3 groups (MAMT: 0%, AMT: 35.7%, DT: 87.5%; p < 0.05). Although the tear secretion was reduced in all groups, it was significantly lower in the DT group compared with the MAMT and AMT groups (p < 0.05).

CONCLUSIONS

Paraquat-induced ocular injuries can lead to whole ocular surface damage. MAMT treatment in a timely manner can effectively promote the repair of the ocular surface and reduce the complications from symblepharon.

Research on mouse model of grade II corneal alkali burn

AIM

To choose appropriate concentration of sodium hydroxide (NaOH) solution to establish a stable and consistent corneal alkali burn mouse model in grade II.

METHODS

The mice (n=60) were randomly divided into four groups and 15 mice each group. Corneal alkali burns were induced by placing circle filter paper soaked with NaOH solutions on the right central cornea for 30s. The concentrations of NaOH solutions of groups A, B, C, and D were 0.1 mol/L, 0.15 mol/L, 0.2 mol/L, and 1.0 mol/L respectively. Then these corneas were irrigated with 20 mL physiological saline (0.9% NaCl). On day 7 postburn, slit lamp microscope was used to observe corneal opacity, corneal epithelial sodium fluorescein staining positive rate, incidence of corneal ulcer and corneal neovascularization, meanwhile pictures of the anterior eyes were taken. Cirrus spectral domain optical coherence tomography was used to scan cornea to observe corneal epithelial defect and corneal ulcer.

RESULTS

Corneal opacity scores (x±s) were not significantly different between the group A and group B (P=0.097). Incidence of corneal ulcer in group B was significantly higher than that in group A (P=0.035). Incidence of corneal ulcer and perforation rate in group B was lower than that in group C. Group C and D had corneal neovascularization, and incidence of corneal neovascularization in group D was significantly higher than that in group C (P=0.000).

CONCLUSION

Using 0.15 mol/L NaOH can establish grade II mouse model of corneal alkali burns.

Long-term efficacy of glycerine-processed amniotic membrane transplantation in patients with corneal ulcer

PURPOSE

The aim of this study was to determine the long-term treatment efficacy of glycerine-preserved human amniotic membrane transplantation in patients suffering from corneal ulcers.

METHODS

This was a retrospective, non-controlled, monocentric analysis. Included were patients with corneal ulcers that were non-responsive to ointment or contact lenses and had been treated by amniotic membrane transplantation with either the overlay or sandwich procedure. Analysis parameters were visual acuity before and following treatment, recurrence rate and subjective comfort at the last follow-up.

RESULTS

Of the 371 amniotic membrane transplantations that were conducted, 135 surgical treatments in 108 patients (51.9% male, 48.1% female; mean age 63.7 years) met the inclusion criteria. In total, 99 overlay and 36 multilayer amniotic membrane transplantations were performed. The follow-up period was 47.5 ± 66.7 weeks (mean ± SD). The recurrence rate at the last follow-up was 47.8% with overlay membranes and 51.8% with the sandwich technique. There was no significant change in best-corrected visual acuity following treatment with overlays (p = 0.219) or sandwich procedure (p = 0.703). At the last follow-up, 72.1% (overlay) and 78.3% (sandwich) of the patients reported either no pain or increased comfort.

CONCLUSION

The recurrence rates and changes in visual acuity following overlay or sandwich amniotic membrane transplantation in patients suffering from corneal ulcer were lower than reported elsewhere in the literature. More than half of the patients profited from each of the amniotic membrane transplantation techniques with respect to recurrence and postoperative comfort.

Novel implantable composite biomaterial by fibrin glue and amniotic membrane for ocular surface reconstruction

Amniotic membrane transplantation (AMT) is considered a substantial treatment option in the management of ocular surface disorders. However, several inherent drawbacks still remain. The present study devised a novel implantable composite biomaterial of fibrin glue-double layer Amniotic membrane (AM) and evaluated the biomechanical properties and effects on corneal surface reconstruction in alkali-burned rabbit model. Biomechanic parameters were calculated by an electronic universal testing machine. Corneal alkali burning was done in the right eyes of thirty rabbits, which were randomized into three groups of ten animals each. The eyes in group 1 underwent fibrin glue-double layer AMT, the eyes in group 2 underwent ordinary single layer AMT, and the eyes in group 3 (control group) did not undergo any surgical procedure. Healing of corneal epithelial defect, extent of corneal vascularization and corneal clarity were assessed and compared at two time points. One month after surgery, animals were killed and the eyes were processed for histopathology. The fibrin glue-double layer AM composites had more ideal biomechanical properties. In fibrin glue-double layer AM group, the rate of epithelial healing, vascularization inhibition and corneal clarity was significantly better than the other two groups. Novel fibrin glue-double layer AMT with corneal alkali burns is more effective and useful for ocular surface reconstruction and has great potential applications.

The amnion muscle combined graft (AMCG) conduits: a new alternative in the repair of wide substance loss of peripheral nerves

The use of autologous sural nerve grafts is still the current gold standard for the repair of peripheral nerve injuries with wide substance losses, but with a poor rate of functional recovery after repair of mixed and motor nerves, a limited donor nerve supply, and morbidity of donor site. At present, tubulization through the muscle vein combined graft, is a viable alternative to the nerve autografts and certainly is a matter of tissue engineering still open to continuous development, although this technique is currently limited to a critical gap of 3 cm with less favorable results for motor function recovery. In this report, we present a completely new tubulization method, the amnion muscle combined graft (AMCG) technique, that consists in the combination of the human amniotic membrane hollow conduit with autologous skeletal muscle fragments for repairing the substance loss of peripheral nerves and recover both sensory and motor functions. In a series of five patients with loss of substance of the median nerve ranging 3-5 cm at the wrist, excellent results graded as S4 in two cases, S3+ in two cases, and S3 in one case; M4 in four cases and M3 in one case were achieved. No iatrogenic damage due to withdrawal of a healthy nerve from donor site was observed. This technique allows to repair extensive loss of substance up to 5 cm with a good sensory and motor recovery. The AMCG thus may be considered a reasonable alternative to traditional nerve autograft in selected clinical conditions.

A novel use of amniotic membrane for fingertip injuries

OBJECTIVE

Fingertip injuries, which are the most common hand injury, represent management challenges for hand surgeons. Full thickness skin grafts are routinely used to cover the fingertip site, but has significant donor site morbidity. As amniotic membranes (AM) are used as a dressing substitute in burns, we decided to evaluate the efficacy of AM as a biologic wound dressing material for coverage of these injuries.

METHOD

In this clinical study, 30 patients with full-thickness zone 1 fingertip skin loss were included. The patients were divided into 2 groups using the block randomisation method. In the first group, a skin graft was used for coverage and in the second group, AM was used. All patients were operated on by the same hand surgeon between February 2012 to October 2012. The minimum follow-up period was 6 months. Two point discrimination (T.P.D), light touch, healing time, days lost from work and infection rate were evaluated and recorded.

RESULTS

This study recruited 30 patients with full-thickness zone 1 fingertip skin loss (age range 13-47 years). Fingertips in both groups were assessed. T.P.D, light touch and days lost from work were significantly lower in the AM group than in the skin graft group. Healing time was lower in the skin graft group. In the both groups, no infection was detected. Patients of both groups were satisfied of their treatment and healing progress.

CONCLUSION

Our results showed the effectiveness and safety of AM for the treatment of fingertip amputation, which can produce better sensation and functional outcomes than skin graft transplantations.