Introduction: Ischemic wounds are a very intractable disease. Although the treatment of this disease is required, many patients cannot undergo revascularization surgery due to their severe comorbidity. Therefore, it is necessary to develop minimally invasive treatment. Human amniotic membrane (hAM) has various characteristics that make it potentially useful as a wound dressing material. We found that fresh hAM promotes the healing of ischemic wounds. However, fresh hAM is occasionally unavailable, and cryopreserved hAM would be more convenient for clinical use. This study aimed to examine the efficacy of cryopreserved hAM as a wound dressing material for ischemic wounds.
Methods: Human amniotic membrane was collected from delivered placentas with the consent of pregnant women who underwent an elective cesarean section at full term. Collected hAM was immediately cryopreserved in PBS after washing out blood. Cryopreserved hAM was used within 6 hours after thawing. Ischemic wounds were made on the abdominal wall of male rats (SD, nine weeks old, 300-350 g) by ligating the arteriovenous and nerve bundles of the inferior abdominal wall and excising the abdomen skin with a diameter of 2.0 cm.
Microvessel density (MVD) as an index of angiogenesis was measured by double staining with anti-α-SMA and anti-CD34 antibodies. The density of the number of blood vessels and the wound area were compared between the hAM group and the control group.
Results: No significant wound area reduction after seven days was observed in the two groups (hAM group vs. control group; 291.3 vs. 235.5 mm2, p = 0.26). The mean value of MVD was significantly higher in the hAM group than in the control group (21.1 vs. 16.4, p = 0.0039). Histological evaluation showed no evident rejection of the hAM in this study.
Conclusions: This study showed the angiogenesis-promoting effects of cryopreserved hAM but did not reveal wound-healing effects. The mechanism of the loss of wound healing effect through hAM cryopreservation requires further investigation.