This study will evaluate the effect of intravenous injection of umbilical cord tissue derived mesenchymal stem cells (UMSCs) on the improvement of renal function in patients with chronic kidney disease (CKD) at stage 3 or 4, with the change of estimated glomerular filtration rate (eGFR) as the primary endpoint, and other changes in renal function laboratory indicators, changes in other organ system function laboratory indicators, and adverse reaction events as secondary endpoints. This trial aims to further evaluate the efficacy and safety of UMCSs in CKD patients, and provide new insights into expanding the clinical treatment strategies, delaying the progression and improving the prognosis of CKD patients.

Inclusion Criteria:

• Agreement to participate in the trial and provision of signed written informed consent
• Pathological diagnosis of diabetic nephropathy or hypertensive renal damage
• 15 ≤ eGFR < 60 mL/min/1.73m², UACR > 300 mg/g
• Age ≥ 18 years

Exclusion Criteria:

• Extremely severe anemia (hemoglobin < 30 g/L)
• Received blood product transfusion therapy within 1 month
• Autosomal dominant or recessive polycystic kidney disease (ADPKD)
• History of kidney transplant or other solid organ transplant
• Active systemic or localized infection (e.g., pneumonia, osteomyelitis)
• Allergy to stem cells themselves or stem cell-related culture medium
• History of allergic reaction to cell products (e.g., blood transfusion, platelets)
• History of coagulation disorders (thromboembolism, pulmonary embolism, deep vein thrombosis)
• History of malignancy or current malignant disease
• Elevated tumor markers (AFP, CEA, CA199, CA125, etc.)
• Pregnant women or women with plans for pregnancy within 3 months after MSC therapy
• Participation in drug-related clinical trials within the past 2 months
• Any form of drug abuse, mental illness, or other conditions considered by the investigator as potentially affecting the trial's validity or the subject's health