Clinical studies using stem cells for treatment of retinal diseases: state of the art / Estudos clínicos com uso de células-tronco para tratamento de doenças da retina: estado da arte

ABSTRACT Degenerative retinal diseases such as retinitis pigmentosa, Stargardt's macular dystrophy, and age-related macular degeneration are characterized by irreversible loss of vision due to direct or indirect photoreceptor damage. No effective treatments exist, but stem cell studies have shown promising results. Our aim with this review was to describe the types of stem cells that are under study, their effects, and the main clinical trials involving them.

RESUMO As doenças degenerativas da retina, como retinose pigmentar, distrofia macular de Stargardt e degeneração macular relaciona à idade, são caracterizadas por perda irre versível da visão devido a danos diretos ou indiretos aos fotorreceptores. Não existem tratamentos eficazes, porém os estudos com células-tronco mostraram resultados promissores. Nosso objetivo com esta revisão foi descrever os tipos de células-tronco em estudo, seus efeitos e os principais ensaios clínicos que as envolvem.

Clinical studies using stem cells for treatment of retinal diseases: state of the art.

Degenerative retinal diseases such as retinitis pigmentosa, Stargardt's macular dystrophy, and age-related macular degeneration are characterized by irreversible loss of vision due to direct or indirect photoreceptor damage. No effective treatments exist, but stem cell studies have shown promising results. Our aim with this review was to describe the types of stem cells that are under study, their effects, and the main clinical trials involving them.

Intravitreal Use of a Bone Marrow Mononuclear Fraction (BMMF) Containing CD34+ Cells in Patients with Stargardt Type Macular Dystrophy.

To assess the therapeutic potential and the safety of intravitreous use of a bone marrow mononuclear fraction (BMMF) containing CD34+ cells in patients with Stargardt type macular dystrophy. The study was conducted on 10 patients with Stargardt dystrophy with worse eye visual acuity ≤ 20/125. A bone marrow aspirate was obtained from all patients, and after processing in the cell therapy center (CTC), 0.1 ml of the intravitreous BMMF suspension was injected into the eye with worse visual acuity. A sham injection was performed in the contralateral eye. The patients were evaluated at baseline and one, three, and six months after the injection. All of them were submitted to measurement of best corrected visual acuity (BCVA), microperimetry, multifocal electroretinography (mfERG) and full field electroretinography (ffERG), autofluorescence (AF), and optical coherence tomography (OCT). Fluorescein angiography was also performed before and six months after the injection. All patients completed the six-month period of evaluation. Mean visual acuity of the treated eye was 1.1 logMAR (20/250) before intravitreous (IV) injection, 0.96 logMAR (20/200+2) one month after injection, and 0.92 logMAR (20/160-1) 3 months after injection. In the untreated eye, mean VA was 1.0 logMAR (20/200) at baseline and 0.96 logMAR (20/200+2) and 0.94 logMAR (20/160-2) one and three months after injection, respectively. In the treated group, VA at baseline ranged from best acuity of 20/125-1 to worst acuity of 20/640+2, going through 20/100+2 and 20/400 during the first month. In the untreated group, BCVA ranged from 20/100+2 to 20/400 at baseline and from 20/100 to 20/400 after one month. The results for the treated group differed significantly at all follow-up times, whereas no significant difference was observed in the untreated group. Regarding the mean sensitivity of microperimetry, although there was improvement throughout all months, a significant difference occurred only during the first month. In the untreated eye, there was no significant difference in any analysis. Angiofluoresceinography did not reveal neovessel formation or tumor growth. The remaining exams were used in order to aid the diagnosis. The results indicate that the use of intravitreous BMMF in patients with Stargardt dystrophy is safe and is associated with a discrete improvement of BCVA and microperimetry in the treated eye compared to the untreated one.

Intravitreal use of bone marrow mononuclear fraction containing CD34+ stem cells in patients with atrophic age-related macular degeneration.

PURPOSE: To evaluate the therapeutic potential and safety of intravitreal injections of bone marrow mononuclear fraction (BMMF) containing CD34+ cells in patients with atrophic age-related macular degeneration (AMD). METHODS: Ten patients with atrophic AMD and best-corrected visual acuity (BCVA) in the worse-seeing eye of ≤20/100 were enrolled in this study. The bone marrow from all patients was aspirated and processed for mononuclear cell separation. A 0.1 mL suspension of BMMF CD34+ cells was injected into the vitreous cavity of the worse-seeing eye. Patients were evaluated at Baseline and 1,3,6,9 and 12 months after injection. Ophthalmic evaluation included BCVA measurement, microperimetry, infrared imaging, fundus autofluorescence and SD-optical coherence tomography at all study visits. Fluorescein angiography was performed at Baseline and at 6 and 12 months after intravitreal therapy. RESULTS: All patients completed the 6-month follow-up, and six completed the 12-month follow-up. Prior to the injection, mean BCVA was 1.18 logMAR (20/320-1), ranging from 20/125 to 20/640-2, and improved significantly at every follow-up visit, including the 12-month one, when BCVA was 1.0 logMAR (20/200) (P<0.05). Mean sensitivity threshold also improved significantly at 6, 9 and 12 months after treatment (P<0.05). Considering the area of atrophy identified by fundus autofluorescence, significant mean BCVA and mean sensitivity threshold improvement were observed in patients with the smallest areas of atrophy. Fluorescein angiography did not identify choroidal new vessels or tumor growth. CONCLUSION: The use of intravitreal BMMF injections in patients with AMD is safe and is associated with significant improvement in BCVA and macular sensitivity threshold. Patients with small areas of atrophy have a better response. The paracrine effect of CD34+ cells may explain the functional improvement observed; however, larger series of patients are necessary to confirm these preliminary findings.

Influence of VEGF-C936T genetic variant on age-related macular degeneration.

PURPOSE: To evaluate the association between the VEGF-C936T polymorphism and serum vascular endothelial growth factor (VEGF) levels, lifestyle, and demographic parameters in patients with age-related macular degeneration (AMD). METHODS: A total of 183 individuals were enrolled in the present study, including 88 patients with AMD receiving clinical and pharmacological treatment (study group, SG) and 95 individuals without AMD as controls (control group, CG). The presence of the VEGF-C936T polymorphism and serum VEGF levels were determined using polymerase chain reaction/restriction fragment length polymorphism and enzyme-linked immunosorbent assay, respectively. Significance was set at P<0.05 for all statistical analyses. RESULTS: The homozygous wild-type genotype (CC) and the C allele were predominant in both groups (P=0.934 and P=0.938, respectively). Serum VEGF levels (assessed in 57% and 31% of patients in the SG and CG, respectively) were comparable between groups (SG, 307.9 ± 223.6 pg/mL; CG, 305.1 ± 212.3 pg/mL; P=0.955). A significantly higher prevalence of smoking (44% vs 25%; P=0.01) and hypertension (66% vs 48%; P=0.025) was observed in the SG than in the CG. The distribution of alcohol consumption and dyslipidemia was similar between groups (P>0.05). CONCLUSIONS: In the present study group of Brazilian patients, the VEGF-C936T polymorphism was not found to be associated with age-related macular degeneration. However, smoking and systemic arterial hypertension (SAH) were found to be potential independent risk factors for the development of age-related macular degeneration. Comparable serum VEGF levels in both study groups may reflect the efficacy of pharmacological treatment of AMD.

Influence of VEGF-C936T genetic variant on age-related macular degeneration / Influência da variante genética VEGF-C936T na degeneração macular relacionada à idade

ABSTRACTPurpose:To evaluate the association between the VEGF-C936T polymorphism and serum vascular endothelial growth factor (VEGF) levels, lifestyle, and demographic parameters in patients with age-related macular degeneration (AMD).Methods:A total of 183 individuals were enrolled in the present study, including 88 patients with AMD receiving clinical and pharmacological treatment (study group, SG) and 95 individuals without AMD as controls (control group, CG). The presence of the VEGF-C936T polymorphism and serum VEGF levels were determined using polymerase chain reaction/restriction fragment length polymorphism and enzyme-linked immunosorbent assay, respectively. Significance was set at P<0.05 for all statistical analyses.Results:The homozygous wild-type genotype (CC) and the C allele were predominant in both groups (P=0.934 and P=0.938, respectively). Serum VEGF levels (assessed in 57% and 31% of patients in the SG and CG, respectively) were comparable between groups (SG, 307.9 ± 223.6 pg/mL; CG, 305.1 ± 212.3 pg/mL; P=0.955). A significantly higher prevalence of smoking (44% vs 25%; P=0.01) and hypertension (66% vs 48%; P=0.025) was observed in the SG than in the CG. The distribution of alcohol consumption and dyslipidemia was similar between groups (P>0.05).Conclusions:In the present study group of Brazilian patients, the VEGF-C936T polymorphism was not found to be associated with age-related macular degeneration. However, smoking and systemic arterial hypertension (SAH) were found to be potential independent risk factors for the development of age-related macular degeneration. Comparable serum VEGF levels in both study groups may reflect the efficacy of pharmacological treatment of AMD.

RESUMOObjetivo:Avaliar a associação entre o polimorfismo VEGF-C936T, níveis séricos de VEGF (vascular endothelial growth factor), hábitos de vida e antecedentes pessoais em pacientes com degeneração macular relacionada à idade (DRMI).Métodos:Foram estudados 183 indivíduos: 88 pacientes com degeneração macular relacionada à idade, em tratamento clínico e medicamentoso (Grupo Estudo - GE) e 95 indivíduos sem sinais clínicos da doença (Grupo Controle - GC). O polimorfismo VEGF-C936T e os níveis séricos de VEGF foram analisados por PCR/RFLP e ELISA, respectivamente. Admitiu-se nível de significância para P<0.05.Resultados:O genótipo homozigoto selvagem (CC) prevaleceu em ambos os grupos (P=0,934), assim como o alelo C (P=0,938). Os níveis séricos de VEGF, analisados em 57% de SG e em 31% de CG, apresentaram valores semelhantes entre pacientes e controles (GE=307,9 ± 223,6 pg/mL; GC=305,1 ± 212,3 pg/mL; P=0,955). Notou-se maior frequência de tabagismo (44%) e hipertensão arterial sistêmica (66%) em GE versus GC (25%; 48%; P=0,01; P=0,025, respectivamente). A distribuição de etilismo e dislipidemia foi semelhante entre os grupos (P>0,05).Conclusões:Em nosso estudo com pacientes brasileiros, o polimorfismo VEGF-C936T não se associa com degeneração macular relacionada à idade, por outro lado, tabagismo e HAS são potencialmente fatores de risco independentes para a doença, enquanto níveis de VEGF semelhantes em ambos os grupos podem refletir o sucesso do tratamento farmacológico.

Association of high-density lipoprotein and apolipoprotein E genetic variants with age-related macular degeneration.

PURPOSE: This study aimed to evaluate the association of age-related macular degeneration (AMD) with apolipoprotein E (APOE) variants and serum lipid profiles, including levels and fractions of total serum cholesterol (TC), low-density lipoprotein cholesterol (LDLc), and high-density lipoprotein cholesterol (HDLc), and triglycerides (TG). METHODS: Genotyping of APOE-HhaI was performed in 134 patients (study group, SG) and 164 individuals without AMD (control group, CG), aged 50-89 years. Lipid profiles were analyzed in a subgroup of 30 subjects of both groups, matched according to age and sex. The significance level was set at P<0.05. RESULTS: APOE E3/E3 was more prevalent (SG=74.6%; CG=77.4%), with no difference between both groups (P=0.667). The same result was observed for risk genotypes (APOE E -/2: SG=7.4%; CG=10.3%, P=0.624). Serum levels of TC, LDLc, and TG revealed similar median values between SG (193.5, 116, and 155 mg/dL, respectively) and CG (207.5, 120, and 123.5 mg/dL, respectively; P >0.05). For HDLc, a higher median value was observed in SG (53.3 mg/dL) versus CG (42.5 mg/dL; P=0.016). Logistic regression analysis showed the same value, and the HDLc/TC ratio was -11.423 (P=0.014), as also confirmed by an increase in HDLc in SG. The association between lipid profiles and apolipoprotein E genotypes was similar in both groups (P>0.05). CONCLUSION: APOE-HhaI is not associated with AMD. However, an increase in serum HDLc level appears to exert a protective effect against the disease, irrespective of the genetic variants of apoE.

Association of high-density lipoprotein and apolipoprotein E genetic variants with age-related macular degeneration / Associação de lipoproteína de alta densidade e variantes genéticas da apolipoproteína E com degeneração macular relacionada à idade

Purpose: This study aimed to evaluate the association of age-related macular degeneration (AMD) with apolipoprotein E (APOE) variants and serum lipid profiles, including levels and fractions of total serum cholesterol (TC), low-density lipoprotein cholesterol (LDLc), and high-density lipoprotein cholesterol (HDLc), and triglycerides (TG). Methods: Genotyping of APOE-HhaI was performed in 134 patients (study group, SG) and 164 individuals without AMD (control group, CG), aged 50-89 years. Lipid profiles were analyzed in a subgroup of 30 subjects of both groups, matched according to age and sex. The significance level was set at P<0.05. Results: APOE E3/E3 was more prevalent (SG=74.6%; CG=77.4%), with no difference between both groups (P=0.667). The same result was observed for risk genotypes (APOE E -/2: SG=7.4%; CG=10.3%, P=0.624). Serum levels of TC, LDLc, and TG revealed similar median values between SG (193.5, 116, and 155 mg/dL, respectively) and CG (207.5, 120, and 123.5 mg/dL, respectively; P >0.05). For HDLc, a higher median value was observed in SG (53.3 mg/dL) versus CG (42.5 mg/dL; P=0.016). Logistic regression analysis showed the same value, and the HDLc/TC ratio was -11.423 (P=0.014), as also confirmed by an increase in HDLc in SG. The association between lipid profiles and apolipoprotein E genotypes was similar in both groups (P>0.05). Conclusion: APOE-HhaI is not associated with AMD. However, an increase in serum HDLc level appears to exert a protective effect against the disease, irrespective of the genetic variants of apoE. .

Objetivo: Este estudo teve como objetivo avaliar a associação de degeneração macular relacionada à idade (DMRI) com variantes de alipoproteína E (APOE) e perfil lipídico sérico, incluindo níveis séricos de colesterol total (TC) e frações de proteínas relacionadas a receptor de LDL (LDLc) e HDL colesterol (HDLc), e triglicérides (TG). Métodos: Realizouse genotipagem de APOE-HhaI em 134 pacientes (grupo de estudo SG) e 164 indivíduos sem a doença (grupo controle CG), na faixa etária entre 5089 anos. O perfil lipídico sérico foi analisado em um subgrupo de 30 indivíduos de ambos os grupos, pareados por idade e sexo. Admitiuse nível de significância para valorP<0,05. Resultados: APOE E3/E3 prevaleceu (SG=74,6%; CG=77,4%), sem diferença entre os grupos (P=0,667), o mesmo ocorreu para genótipos de risco (APOE /E2: SG=7,4%; CG=10,3%,P=0,624).Níveis séricos de TC, LDLc e TG mostraram medianas semelhantes entre SG (193,5; 116; 155 mg/dL, respectivamente) e CG (207,5; 120; 123,5 mg/dL respectivamente; P>0,05). Para HDLc notouse valor de mediana elevado em SG (53,3 mg/dL) versus CG (42,5 mg/dL; P=0,016), constatado também na análise de regressão logística, cuja razão HDLc/TC mostrou coeficiente 11,423 (P=0,014), confirmando acréscimo de HDLc em SG. A relação entre perfil lipídico sérico e genótipos de APOE mostrou semelhança entre os grupos (P>0,05). Conclusão: APOE-HhaI não se associa a DMRI, no entanto, o acréscimo no nível sérico de HDLc parece ter efeito protetor contra a doença, independente de variantes genéticas da apoE. .