The purpose of the present study is to evaluate the safety and exploratory efficacy of the medical collagen membrane with umbilical cord derived mesenchymal stem cells in the treatment of patients with skin defects.

Inclusion Criteria:

• Age between 18 and 70, borh gender.
• Patient able and willing to sign informed consent and comply with study procedures.
• Women of childbearing potential must use birth control pills, barriers or abstinence and have a negative pregnancy test.
• Deep partial or full thickness skin defect of at least 9 cm2 requiring surgical wound coverage due to: burn injury, diabetic foot ulcer or wounds caused by mechanical damage or iatrogenic injury.

Exclusion Criteria:

• Patient refusal.
• Patient has a documented history of allergy or sensitivity to any of the animal products used in preparation of skin substitute. These products include bovine blood, bovine collagen, and bovine collagenase.
• Patient has a documented history of allergy or sensitivity to any of the antimicrobials or reagents used in preparation and application of skin substitute including the irrigation solution used before and after grafting.
• Patient has a current diagnosis of an invasive burn wound infection in unexcised burn wound.
• Patient has tunnels or sinus tracts that cannot be completely debrided.
• Serious primary diseases of the liver, kidney and hematopoietic system, Abnormal liver function(glutamic-pyruvic transaminase(ALT), glutamicoxalacetic transaminase (AST) is 2 times higher than the normal value), creatinine(Cr) is higher than the upper limit of the normal value.
• Other clinical trial participants within 3 months.
• A random blood sugar reading >/=450 mg/dL.
• Investigators judge other conditions not suitable for inclusion.