The purpose of this research study is to test the safety and benefit of a human cord blood derived stem cell infusion as a treatment for individuals with post COVID-19 neurological problems. Participants in the study will have 6 clinic visits over a 12 to 14 mo. period with each visit lasting 2 to 6 hours. Participants will receive 1 stem cell infusion at study visit #3. Participants will have a brain PET and MRI scan at the baseline and 6mo. post-infusion visits. Follow-up safety assessments will be conducted at 6mo. and 1yr. after the stem cell infusion.

This is a non-randomized, Phase 1/2a dose escalation study using allogenic cord tissue MSC's in adults with chronic neurological symptoms following an acute COVID-19 infection.

Inclusion Criteria:

1. Adults between 18 and 55 years of age.
2. Documented history of COVID-19 infection with resulting neurological sequela.
3. Post-Covid-19 Functional Status score of grades 3 or 4.
4. Chronic neurological symptoms defined as anxiety/depression, pain syndromes, sleep disorders, and /or memory disorders ("brain fog") persisting 6 months after an acute COVID-19 infection.
5. Ability to obtain consent from the subject.
6. Ability to communicate in English or Spanish (required for validated neurocognitive outcome testing).

Exclusion Criteria:

1. Known history of:

   1. intellectual deficiency or psychiatric conditions likely to invalidate our ability to assess changes in cognition or behavior,
   2. recently treated infection,
   3. renal disease or altered renal function (screening serum creatinine > 1.5 mg/dL),
   4. hepatic disease or altered liver function (screening SGPT > 150 U/L and/or T. Bilirubin >1.3 mg/dL),
   5. cancer,
   6. immunosuppression (screening WBC < 3, 000 cells/ml),
   7. HIV+,
   8. chemical or ETOH dependency that in the opinion of the investigator would preclude participation in the study,
   9. acute or chronic lung disease requiring significant medication/oxygen supplementation,
   10. bleeding disorders including immune-mediated heparin-induced thrombocytopenia,
   11. hypercoagulable disorders (Protein C, S, ATIII deficiencies), Factor V Leiden,
   12. known sensitivity to heparin, Lovenox, and pork products,
   13. individuals with mechanical prosthetic heart valves.

2. Pulse oximetry oxygen saturation <93% on room air.

3. Other acute or chronic medical conditions that, in the opinion of the investigator, may increase the risks associated with study participation.

4. For women of childbearing potential, a positive pregnancy test at the screening visit or, for both women and men, unwillingness to comply with acceptable methods of birth control during the study.

5. Previous or concurrent participation in an interventional drug or biological study.

6. Inability to undergo the diagnostic tests (PET/DT-MRI) or unwilling/unable to cooperate with the diagnostic tests and outcome assessments.

7. Unwilling or unable to return for follow-up study visits.

8. Prisoner/Incarcerated.