Laura Liu

Subretinal Implantation of Retinal Pigment Epithelial Cells Derived From Human Embryonic Stem Cells: Improved Survival When Implanted as a Monolayer

PURPOSE To evaluate cell survival and tumorigenicity of human embryonic stem cell-derived retinal pigment epithelium (hESC-RPE) transplantation in immunocompromised nude rats. Cells were transplanted as a cell suspension (CS) or as a polarized monolayer plated on a parylene membrane (PM). METHODS Sixty-nine rats (38 male, 31 female) were surgically implanted with CS (n = 33) or PM (n = 36). Cohort subsets were killed at 1, 6, and 12 months after surgery. Both ocular tissues and systemic organs (brain, liver, kidneys, spleen, heart, and lungs) were fixed in 4% paraformaldehyde, embedded in paraffin, and sectioned. Every fifth section was stained with hematoxylin and eosin and analyzed histologically. Adjacent sections were processed for immunohistochemical analysis (as needed) using the following antibodies: anti-RPE65 (RPE-specific marker), anti-TRA-1-85 (human cell marker), anti-Ki67 (proliferation marker), anti-CD68 (macrophage), and anti-cytokeratin (epithelial marker). RESULTS The implanted cells were immunopositive for the RPE65 and TRA-1-85. Cell survival (P = 0.006) and the presence of a monolayer (P < 0.001) of hESC-RPE were significantly higher in eyes that received the PM. Gross morphological and histological analysis of the eye and the systemic organs after the surgery revealed no evidence of tumor or ectopic tissue formation in either group. CONCLUSIONS hESC-RPE can survive for at least 12 months in an immunocompromised animal model. Polarized monolayers of hESC-RPE show improved survival compared to cell suspensions. The lack of teratoma or any ectopic tissue formation in the implanted rats bodes well for similar results with respect to safety in human subjects.

A Novel Approach for Subretinal Implantation of Ultrathin Substrates Containing Stem Cell-Derived Retinal Pigment Epithelium Monolayer

Objective: To evaluate the feasibility of a new technique for the implantation of ultrathin substrates containing stem cell-derived retinal pigment epithelium (RPE) cells into the subretinal space of retina-degenerate Royal College of Surgeon (RCS) rats. Methods: A platform device was used for the implantation of 4-µm-thick parylene substrates containing a monolayer of human embryonic stem cell-derived RPE (hESC-RPE). Normal Copenhagen rats (n = 6) and RCS rats (n = 5) were used for the study. Spectral-domain optical coherence tomography (SD-OCT) scanning and histological examinations were performed to confirm placement location of the implant. hESC-RPE cells attached to the substrate before and after implantation were evaluated using standard cell counting techniques. Results: SD-OCT scanning and histological examination revealed that the substrates were precisely placed in the rat’s subretinal space. The hESC-RPE cell monolayer that covered the surface of the substrate was found to be intact after implantation. Cell counting data showed that less than 2% of cells were lost from the substrate due to the implantation procedure (preimplantation count 2,792 ± 74.09 cells versus postimplantation count 2,741 ± 62.08 cells). Detailed microscopic examination suggested that the cell loss occurred mostly along the edges of the implant. Conclusion: With the help of this platform device, it is possible to implant ultrathin substrates containing an RPE monolayer into the rat’s subretinal space. This technique can be a useful approach for stem cell-based tissue bioengineering techniques in retinal transplantation research.

The Incidence of Adjacent Segment Disease Requiring Surgery After Anterior Cervical Diskectomy and Fusion: Estimation Using an 11-Year Comprehensive Nationwide Database in Taiwan

BACKGROUND The incidence of symptomatic adjacent segment disease (ASD) after anterior cervical diskectomy and fusion (ACDF) was reported as 2.9%/y in a previous cohort of 374 patients. Few other data corroborate the incidence and natural history of ASD. OBJECTIVE To calculate the incidence of ASD after ACDF that required secondary fusion surgery. METHODS The retrospective study used an 11-year nationwide database to analyze the incidences. All patients who underwent ACDF for cervical disk diseases were identified through diagnostic and procedure codes. Kaplan-Meier and Cox regression analyses were performed. RESULTS From 1997 to 2007, covering 241 800 725.8 person-years, 19 385 patients received ACDF and 568 had ≥ 2 ACDF operations. The incidence of secondary ACDF operations was 7.6 per 1000 person-years. At the end of the 10-year cohort, 94.4% of patients who had received 1 ACDF remained free from secondary ACDF. The average time interval between the first and second ACDF was 23.3 months. After adjustment for comorbidities and socioeconomic status, secondary ACDF operations were more likely performed on male patients (hazard ratio = 1.27; P = .008) 15 to 39 years of age (hazard ratio = 1.45; P = .009) and 40 to 59 years of age (hazard ratio = 1.41, P = .002, respectively). CONCLUSION Repeat ACDF surgery for ASD cumulated steadily in an annual incidence of approximately 0.8%, much lower than the reported incidence of symptomatic ASD. However, at the end of this 10-year cohort, a considerable portion of patients (5.6%) received a second operation. Younger and male patients are more likely to receive such second operations.

Reducing the incidence of early postoperative vitreous haemorrhage by preoperative intravitreal bevacizumab in vitrectomy for diabetic tractional retinal detachment

Acta Ophthalmol. 2010: 88: 635–640

Age, Sex, and Socio-Economic Status Affect the Incidence of Pediatric Spinal Cord Injury: An Eleven-Year National Cohort Study

Background Few studies focus on pediatric spinal cord injury (SCI) and there is little information regarding the cause, anatomic level, and high risk population of SCI in children. This study aims to investigate the incidence and risk factors of pediatric SCI. Methods A nationwide cohort of 8.7 million children aged<18 years in an 11-year period was analyzed for causes, age at injury, anatomic sites, disability, and familial socio-economic factors. Incidence rates and Cox regression analysis were conducted. Results A total of 4949 SCI patients were analyzed. The incidence rates of cervical, thoracic, lumbar, and other SCI were 4.06, 0.34, 0.75, and 0.85 per 100,000 person-years, respectively. The proportional composition of gender, age, and socio-economic status of SCI patients were significantly different than those of non-SCI patients (all p<0.001). Male children were significantly more likely to have SCI than females in both the cervical and the other SCI groups [Incidence rate ratio (IRR) = 2.03 and 1.52; both p<0.001]. Young adults and teenagers were also significantly more likely to have SCI than pre-school age children in the cervical SCI (IRR = 28.55 and 10.50, both p<0.001) and other SCI groups (IRR = 18.8 and 7.47, both p<0.001). Children in families of lower socio-economic status were also significantly more likely to have SCI (p<0.05). Conclusions In the pediatric population, the overall SCI incidence rate is 5.99 per 100,000 person-years, with traumatic cervical SCI accounting for the majority. The incidence rate increases abruptly in male teenagers. Gender, age, and socio-economic status are independent risk factors that should be considered.

Endophthalmitis caused by Pseudomonas aeruginosa in Taiwan.

Purpose: To investigate the clinical settings, treatment given, and visual outcomes for eyes with Pseudomonas aeruginosa endophthalmitis in Taiwan. Methods: This is a retrospective, noncomparative, consecutive case series. Medical records were reviewed in 72 eyes of 71 patients with culture-proven P. aeruginosa endophthalmitis between January 1997 and December 2007. Results: The clinical settings included keratitis/scleritis (44.4%), cataract surgery (15.3%), penetrating keratoplasty (13.9%), endogenous source (12.5%), trauma (6.9%), penetrating keratoplasty with cataract surgery (2.8%), trabeculectomy with cataract surgery (1.4%), trabeculectomy (1.4%), and secondary implant (1.4%). Initial visual acuity ranged from counting fingers to no light perception. Final visual acuity was better than 5/200 in 6 of 72 eyes (8.3%), 4/200 to hand motions in 4 eyes (5.6%), and light perception to no light perception in 62 eyes (86.1%). In vitro testing, the susceptibility patterns of organisms isolated were as follows: ceftazidime (100%), cefepime (100%), aztreonam (100%), imipenem (99%), amikacin (94%), and gentamicin (86%). Five of 16 eyes (31.3%) that underwent primary or secondary pars plana vitrectomy with intravitreal antibiotics achieved a final visual acuity of 5/200 or better compared with 1 of 45 eyes (2.2%) treated with 1 or multiple vitreous tap(s) and intravitreal antibiotics (Fishers exact test, P = 0.004). Conclusion: Despite early diagnosis and treatment with intravitreal antibiotics, visual acuity outcomes were generally poor.

Blood-Assisted Internal Limiting Membrane Peeling for Macular Hole Repair

PURPOSE To evaluate the efficacy of autologous heparinized whole blood in assisting internal limiting membrane (ILM) peeling by coating the ILM for macular hole (MH) repair. DESIGN Prospective, interventional case series. PARTICIPANTS Twenty-nine patients (32 eyes) who underwent blood-assisted ILM peeling for MH repair. METHODS Patients in whom stage 2-4 idiopathic MHs had developed and who desired surgery were enrolled in this study. After core vitrectomy, autologous heparinized whole blood was applied to cover the macula and to coat the surface of the macular area in the fluid-filled vitreous cavity. The redundant blood was removed and only a very thin film of blood was left on the macular area. The blood-coated ILM was removed by forceps in a circular fashion. To confirm the removed membrane was the ILM, the first 10 specimens were examined by electron microscopy (EM). MAIN OUTCOME MEASURES The MH closure rate, the interval mean visual acuity (before and after surgery), retinal changes, and the EM results of the ILM specimens. RESULTS All 32 eyes in 29 patients completed 12 months of follow-up. The ILM were coated by autologous heparinized whole blood, removed without difficulty, and confirmed by EM. The whole blood highlighted the contrast of the coated and noncoated areas during the ILM peeling procedure. The MHs were closed in all surgical eyes with a single surgery (100%). Compared with study entry, the mean logMAR best-corrected visual acuity 12 months after surgery improved significantly (1.02 and 0.53, respectively; P<0.001). At 12 months of follow-up, 31 eyes (96.9%) had stable or improved vision. No toxic fundus changes were observed during follow-up. CONCLUSIONS Autologous heparinized whole blood coated the ILM and facilitated visibility during ILM peeling. Autologous heparinized whole blood is a cost-effective and useful tool for assisting MH surgery.

Hospitalized osteoporotic vertebral fracture increases the risk of stroke: A population-based cohort study

The association between osteoporosis and cardiovascular diseases has been demonstrated. Higher cardiovascular risk has also been correlated with vertebral fractures. However, the association between osteoporotic vertebral fracture and the possibly higher risk of stroke remains uncertain. This study aimed to evaluate the incidence, risk, and type of stroke in patients with osteoporotic vertebral fracture. Patients with osteoporotic vertebral fracture were identified (n = 380) and 10 age‐ and sex‐matched controls per case (comparison group, n = 3795) were chosen from a nationwide representative cohort of 999,997 people from 1998 to 2005. Both groups were followed‐up for stroke events for 3 years, matched by propensity scores with adjustments for covariates such as comorbidities (ie, hypertension, diabetes, arrhythmia, or coronary heart diseases) and exposure to medications (ie, aspirin, lipid lowering drug, or nitrates), and assessed by Kaplan‐Meier and Cox regression analyses. The incidence rate of stroke in the osteoporotic vertebral fracture group (37.5 per 1000 person‐years; 95% confidence interval [CI], 27.5–51.2) was significantly higher than in the comparison group (14.0 per 1000 person‐years; 95% CI, 12.0–16.4, p < 0.001). Stroke was more likely to occur in the osteoporotic vertebral fracture patients than in the normal controls (crude hazard ratio [HR] 2.68, 95% CI 1.89–3.79, p < 0.001; adjusted HR 2.71, 95% CI 1.90–3.86, p < 0.001). In conclusion, patients with osteoporotic vertebral fracture have a higher risk of stroke (ie, both ischemic and hemorrhagic) and require stroke prevention strategies.

Semipermeable parylene membrane as an artificial Bruch's membrane

This paper investigates the feasibility of a mesh-supported submicron-thick semipermeable parylene-C membrane as an artificial Bruchs membrane for the treatment of age-related macular degeneration (AMD). First, the permeabilities of parylene-C membranes with different thickness were measured and the results showed that as-deposited 0.30µm-thick parylene-C, which has a similar permeability to biological Bruchs membrane, is a good candidate to replace the diseased Bruchs membrane. This was further validated by perfusion cell culture experiments, in which nutrients were supplied to the cultured cells only by permeation through the submicron membrane. It was also found that retinal pigment epithelial (RPE) cells could grow and well-polarize with normal morphology on the membrane Finally, the implantation of the submicron-thick membrane (with in vitro cultured RPE cells) into rats retina was successfully done with the help of a parylene-C/SU-8 microsurgical tool, and the following histological study of the retina showed that the reported thin parylene-C membrane could be a promissing RPE substrate candidate for further study.

Ghost Cell Glaucoma After Intravitreal Bevacizumab for Postoperative Vitreous Hemorrhage Following Vitrectomy for Proliferative Diabetic Retinopathy

BACKGROUND AND OBJECTIVE To report the occurrence of ghost cell glaucoma after intravitreal injection of bevacizumab for the treatment of postoperative vitreous hemorrhage after vitrectomy for proliferative diabetic retinopathy (PDR). PATIENTS AND METHODS Retrospective chart review from August 2006 to December 2007. Patients who had postoperative vitreous hemorrhage after vitrectomy for PDR and received an intravitreal injection of bevacizumab were enrolled in the study. RESULTS Eight eyes of 8 patients (mean age: 46 years) were included. After intravitreal injection of bevacizumab, 4 (50%) eyes had clearance of vitreous hemorrhage. Three eyes developed ghost cell glaucoma within 1 week after intravitreal injection of bevacizumab. Of these, intraocular pressure was controlled in 1 eye through the use of anti-glaucoma medication, whereas the other 2 eyes needed surgical intervention to lower intraocular pressure and subsequently clear the vitreous hemorrhage. CONCLUSION Intravitreal injection of bevacizumab may accelerate the clearance of postoperative vitreous hemorrhage in cases of PDR. However, a high incidence of ghost cell glaucoma was observed. Caution should be exercised when administering an intravitreal injection of bevacizumab for a postoperative vitreous hemorrhage after vitrectomy for PDR.