Inclusion Criteria:  Age 8 ≤ 25 years at time of enrollment. Severe systemic sclerosis or systemic lupus erythematosus based on specific criteria Adequate organ function status No active, untreated infections.  Exclusion Criteria:  Previous hematopoietic stem cell transplant (HSCT) or solid organ transplant Pregnancy Ongoing participation in a clinical trial testing an investigational drug or ongoing receipt of disallowed disease modifying anti-rheumatic drugs (DMARD) Severe comorbidity that jeopardizes the ability of the subject to tolerate therapy