This study is an open prospective clinical trial. The objective is to evaluate the effect of autologous exosomes rich plasma on cutaneous wound healing. The participants are patients with intractable cutaneous ulcers (e.g. rheumatic disease, peripheral arterial disease, chronic venous insufficiency, decubitus or burns). The participants will be treated autologous exosomes rich plasma every day for 28 days. The cutaneous wound healing will be evaluated by the length, width and depth of the wound.

Exosomes are small vesicles 0.03-0.1 μm in size, which are shed from most cell types into the extracellular space via intracellular endocytosis. They are found abundantly in body fluids such as blood. They consist of lipid bilayer so that their structure is stable. They can be preserved for 2 weeks at 4℃. They contain proteins, lipids and nucleic acids including coding or non-coding RNA. Resent studies have revealed that exosomes have an important role in cell-to-cell communication.

The investigators found that serum exosome levels were significantly decreased in scleroderma patients with vascular involvements such as cutaneous ulcers and/or pitting scars compared to in normal subjects. The investigators also elucidated that serum-derived exosomes accelerated cutaneous wound healing in BALB/c mice. Exosome supplementation to cutaneous ulcers seems to have significant therapeutic value.

The objective of present study is to evaluate the effect of exosomes derived from plasma on intractable cutaneous ulcers (e.g. rheumatic disease, peripheral arterial disease, chronic venous insufficiency, decubitus or burns).

Autologous exosomes are obtained from the participants' own plasma. The duration of study is 28days. The cutaneous wound healing will be evaluated at day1, day2, day7, day14, day 21 day 28.

Inclusion Criteria:

Patients with intractable cutaneous ulcers (e.g. rheumatic disease, peripheral arterial disease, chronic venous insufficiency, decubitus or burns)

Exclusion Criteria:

1. Patients who have ulcers with bone involvement.
2. Patients who have ulcers with a history or suspected neoplasia.
3. Patients who are in chemotherapy or radiation therapy on the skin ulcers.
4. Patients with marked immunodeficiency (i.e., patients with severe liver failure, heart failure, hematologic failure or endocrine failure)
5. Patients who have clinical signs of malnutrition or serum albumin <2 mg / dL.
6. Patients who have severe infection.
7. Patients who are pregnant or breastfeeding.
8. Patients who are participating in another study.
9. Patients who are judged inappropriate for this trial by their attending physician.