Treatment of Central Retinal Vein Occlusion Using Stem Cells Study

Study Eye Inclusion/Exclusion Criteria: Inclusion criteria for the study eye: * Clinical diagnosis of central retinal vein occlusion (CRVO) confirmed by review of medical records and screening assessment. * Best Corrected Visual Acuity (BCVA) obtained during the screening period is in the range of 20/40+ to 20/400- (ETDRS letter score in the range of 18 to 73, inclusive). * Duration of vision loss from CRVO \>= 6 months to \<=42 months. Exclusion criteria for the study eye: * Previous eye treatment with intravitreal or periocular steroids, laser or intraocular surgery within 6 months prior to enrollment (i.e., date ICF signed) or treatment expected to be given during the study period. * For eyes requiring treatment to prevent recurrent macular edema, on-going intravitreal anti-VEGF treatment is expected to be given at an interval \< every 8 weeks during the study period or anti-VEGF therapy was started less than 24 weeks prior to informed consent. * History of concurrent ocular herpes infection. * Active non-herpetic eye infection diagnosed within 8 weeks from enrollment (i.e., date Informed Consent Form (ICF) signed). * Glaucoma requiring treatment with more than 2 medications, laser or intraocular surgery. * Active uveitis or history of recurrent uveitis or uveitis involving the posterior segment. * Presence of cataract that is impairing vision. * Presence of lens or lens implant subluxation. * History of ocular trauma that is currently impairing vision. * Any concurrent optic nerve or retinal disease that is visually significant or likely to progress to visual significance during the 1-year study follow-up. The excluded eyes include eyes with AREDS category 2 to 3 age-related macular degeneration (AMD) with foveal involvement of drusen or RPE changes, and any AREDS category 4 AMD eyes. For eyes with ERM, the excluded eyes include eyes with OCT evidence of foveal deformation. For optic nerve disease, eyes with any associated visual field deficit or history of associated CNVM are excluded. For glaucoma eyes, eyes requiring glaucoma laser trabeculectomy or glaucoma surgery to maintain IOP are excluded. * Active retinal or iris neovascularization. * Macular edema requiring on-going therapy or where treatment is expected during the study period, with the exception of anti-VEGF treatment given at an interval of 8 weeks or greater. * Significant media opacity precluding view of the fundus for examination, photography or optical coherence tomography (OCT) including cataract and vitreous haze. * High myopia (\>= 9 diopters) * Amblyopia * Other cause contributing to vision loss at screening. * History of any of the following procedures: corneal transplant, glaucoma surgery, or intraocular silicone oil. Participant-level Inclusion/Exclusion Criteria: Participant-level inclusion criteria: * Age \>=18 years * Female participants of child-bearing potential must not be pregnant or breastfeeding and have a negative urine pregnancy test within 14 days prior to sham injection and/or CD34+ cell injection. * Females of childbearing potential must have had a hysterectomy, be completely abstinent from intercourse or must agree to practice effective contraception for the duration of the study. Acceptable methods of contraception include hormonal contraception, intrauterine device, barrier methods (diaphragm, condom) with spermicide, or surgical sterilization (tubal ligation). * Able and willing to sign informed consent. * Able to keep follow-up appointments for at least 12 months as determined by the investigator. Participant-level exclusion criteria: * Concurrent treatment with an investigational drug or device. * Concurrent use of systemic immunosuppressive therapy or history of use within 3 months prior to enrollment (i.e., date ICF signed). * Concurrent use of anticoagulation therapy except for aspirin without an acceptable safe stopping plan for study treatments. * Known history of coagulopathy or other hematologic abnormality that may put participant at risk for bleeding or infection or raise concerns about quality or quantity of CD34+ cells isolated. * History of allergy to fluorescein dye. * Participant who has had a prior or concomitant malignancy with the exception of the following: 1) adequately treated basal or squamous cell carcinoma of the skin, or 2) any other malignancy from which the patient has remained disease free for more than five years. * Current active systemic infection as evidenced by fever greater than 100.4 or any evidence of systemic infection as determined by the study physician. * Any diagnosis of active infection or vaccination within 8 weeks of study treatment. * Diabetes mellitus with known systemic complications by self-report or physician-determined by medical history or examination. * History of prior radiotherapy to head/neck area. * Poorly controlled hypertension with systolic \> 180 or diastolic \> 95. * Serious medical or psychiatric condition that, in the opinion of the Investigator, would make study participation hazardous to the participant or compromise study findings or would prevent the participant from completing the study. * Any physical characteristic that precludes ability to perform study diagnostic testing.