Intravitreal injection of autologous bone marrow-derived mononuclear cells for hereditary retinal dystrophy: a phase I trial

Long-term effects of intravitreal injection of GMP-grade bone-marrow-derived CD34+ cells in NOD-SCID mice with acute ischemia-reperfusion injury

PURPOSE

To determine long-term safety of intravitreal administration of good manufacturing practice (GMP)-grade human bone-marrow-derived CD34(+) cells in NOD-SCID (nonobese diabetic-severe combined immunodeficiency) mice with acute retinal ischemia-reperfusion injury, a model for retinal vasculopathy.

METHOD

Acute ischemia-reperfusion injury was induced in the right eye of adult NOD-SCID mice (n = 23) by transient elevation of intraocular pressure. Seven days later, 12 injured eyes and 5 normal contralateral eyes were injected each intravitreally with 5 × 10(4) CD34(+) cells isolated under GMP conditions from a healthy human donor bone marrow using an immunomagnetic cell isolation system. The remaining 11 injured eyes were not treated and served as controls. Mice were euthanized 1 day, 4 months, and 8 months later. Both eyes were enucleated and examined by immunohistochemical analysis and hematoxylin and eosin staining. Among mice followed for 8 months, electroretinography (ERG) was performed on both eyes before euthanization. All major organs were examined grossly and histologically after serial sectioning.

RESULTS

Immunohistochemical staining 4 months after injection showed detectable CD34(+) cells in the retinal vasculature. ERG at 8 months after CD34(+) cell injection showed signals that were similar in untreated eyes. Histology of the enucleated eyes injected with CD34(+) cells showed no intraocular tumor or abnormal tissue growth after 8 months. Histologic analysis of all major organs showed no abnormal proliferation of human cells.

CONCLUSIONS

Intravitreal administration of GMP-grade human bone-marrow-derived CD34(+) cells appears to be well tolerated long-term in eyes with acute retinal ischemic injury. A clinical trial will start to further explore this therapy.

Stem cell therapy for retinal diseases: update

Distinct stem cell types have been established from embryos and identified in the fetal tissues and umbilical cord blood as well as in specific niches in many adult mammalian tissues and organs such as bone marrow, brain, skin, eyes, heart, kidneys, lungs, gastrointestinal tract, pancreas, liver, breast, ovaries, and prostate. All stem cells are undifferentiated cells that exhibit unlimited self-renewal and can generate multiple cell lineages or more restricted progenitor populations that can contribute to tissue homeostasis by replenishing the cells or to tissue regeneration after injury. The remarkable progress of regenerative medicine in the last few years indicates promise for the use of stem cells in the treatment of ophthalmic disorders. Experimental and human studies with intravitreal bone marrow-derived stem cells have begun. This paper reviews recent advances and potential sources of stem cells for cell therapy in retinal diseases.

Assessment of "non-recordable" electroretinograms by 9 Hz flicker stimulation under scotopic conditions

To refine methods of electroretinographical (ERG) recording for the analysis of low retinal potentials under scotopic conditions in advanced retinal degenerative diseases. Standard Ganzfeld ERG equipment (Diagnosys LLC, Cambridge, UK) was used in 27 healthy volunteers (mean age 28 ± SD 8.5 years) to define the stimulation protocol. The protocol was then applied in clinical routine and 992 recordings were obtained from patients (mean age 40.6 ± 18.3 years) over a period of 5 years. A blue stimulus with a flicker frequency of 9 Hz was specified under scotopic conditions to preferentially record rod-driven responses. A range of stimulus strengths (0.0000012-6.32 scot. cd s/m² and 6-14 ms flash duration) was tested for maximal amplitudes and interference between rods and cones. Analysis of results was done by standard Fourier Transformation and assessment of signal-to-noise ratio. Optimized stimulus parameters were found to be a time-integrated luminance of 0.012 scot. cd s/m² using a blue (470 nm) flash of 10 ms duration at a repetition frequency of 9 Hz. Characteristic stimulus strength versus amplitude curves and tests with stimuli of red or green wavelength suggest a predominant rod-system response. The 9 Hz response was found statistically distinguishable from noise in 38% of patients with otherwise non-recordable rod responses according to International Society for Clinical Electrophysiology of Vision standards. Thus, we believe this protocol can be used to record ERG potentials in patients with advanced retinal diseases and in the evaluation of potential treatments for these patients. The ease of implementation in clinical routine and of statistical evaluation providing an observer-independent evaluation may further facilitate its employment.

Translational research in retinology

Clinical laboratories are strong, integral partners in personalized health care. Laboratory databases hold a vast amount of data on human phenotypes, genotypes, biomarkers, progression of disease, and response to therapy. These structured and unstructured free text data are critical for patient care and a resource for personalized medicine and translational research. Laboratory data are integrated into many electronic medical records that provide "summary reports" and "trending" to visualize longitudinal patient data. Recent advances in ophthalmology such as gene therapy, cell therapy using stem cells, and also retinal prosthesis explore the potential of translational research marking a new era in research into the diagnosis and treatment of eye diseases.