This study proposes to carefully examine the hypothesis that human inducible pluripotent stem cells (iPSCs) can be effectively employed as a future therapeutic option for individuals with diabetic retinopathy and macular ischemia. iPSCs will be generated from the peripheral blood cells of subjects with diabetes and age matched controls. The human iPSC cells will be used to generate mesoderm cells for injection into the vitreous cavity of diabetic rodents and primate eyes. The ability of mesoderm cells to generate endothelial cells and pericytes in areas of degenerated capillaries will be examined. The human iPSCs will also be used to generate hematopoietic CD34+CD45+ cells. The combination of CD34+CD45+ cells derived from iPSCs and iPSC derived mesoderm will be examined in combination for their potentially beneficial effect to enhance the vessel formation.

Vascular complications due to diabetes mellitus (DM) are the result of sustained vascular injury with insufficient vascular repair. In chronic diabetes, vascular reparative mechanism can be lost resulting in development of microvascular complications (MVC), such as diabetic retinopathy (DR). We assessed the reparative function of progenitor cells that circulate in the peripheral blood of diabetic individuals and found that the vascular wall-derived progenitor cells, endothelial colony forming cells (ECFCs), were depleted in diabetics with MVC. Bone marrow-derived progenitor cells, CD45+CD34+ were dysfunctional in diabetics with MVC. We found that human inducible pluripotent stem cells (hiPSCs)-derived ECFCs displayed the ability to form functional and durable blood vessels in vivo and conferred therapeutic revascularization by connecting with and remaining integrated with host rodent vessels long term. We characterized a mesoderm subset (SSEA5-KNA+ cells) generated from hiPSCs that gives rise to ECFCs. Finally, we used hiPSCs to generate CD34+CD45+ cells and tested the impact of co-administration of these cells with ECFCs within the vitreous. The addition of CD34+CD45+ cells with ECFCs resulted in the enhanced survival, function and reparative ability of the ECFCs. This beneficial effect was mediated by reducing retinal oxidative stress and inflammation.

These novel and paradigm shifting findings led us to hypothesize: the hiPSC-derived-mesoderm subset (SSEA5-KNA+) can be utilized for long term revascularization of vasodegenerative capillaries and their reparative action can be further enhanced by coinjection of CD34+CD45+ cells that provide anti-oxidant and anti-inflammatory effects.

Inclusion Criteria:

• Any man or woman between the ages of 21- 98 years of age will be eligible to participate. To participate in the study as a study subject we will require: a) the subject must either carry the diagnosis of diabetes or be a healthy aged control and b) the patient be willing and have the ability to cooperate with the eye exam and skin punch biopsy protocol.

Exclusion Criteria:

• We will apply the following exclusion criteria: a) evidence of ongoing acute or chronic infection (HIV, Hepatitis B or C, tuberculosis); b) ongoing malignancy; c) cerebral vascular accident or cerebral vascular procedure; d) current pregnancy; e) history of organ transplantation; f) presence of a graft (to avoid any effect of the graft on inflammatory parameters; and g) patients with anemia. Subjects with AMD, glaucoma, uveitis, known hereditary degenerations or other significant ocular complications other than diabetic retinopathy will be excluded.

Patients who have retinal abnormalities other than diabetic retinopathy will be excluded. Patients who have history of malignant disease or hematologic disorder. We will record medications that the patient is taking at the time of biopsy. Baseline characteristics will also be recorded, including age, lipid parameters, body mass index, blood pressure, smoking history, antioxidant intake and use of nutritional supplements.