Scientific (Exp)/research
Intracellular delivery of adenosine triphosphate enhanced healing process in full-thickness skin wounds in diabetic rabbits

https://doi.org/10.1016/j.amjsurg.2009.05.040Get rights and content

Abstract

Background

Small unilamellar lipid vesicles were used to encapsulate adenosine triphosphate (ATP-vesicles) for intracellular energy delivery and were tested for diabetic skin wounds in rabbits.

Methods

Diabetes was induced by alloxan. The mean peak blood glucose concentration was 505 mg/dL. One ear was made ischemic and 80 full-thickness wounds were created in 10 animals. ATP-vesicles or saline was used and healing was compared.

Results

On the non-ischemic ears, mean closure time for ATP-vesicles–treated wounds was 13.7 days versus 16.4 days for saline-treated wounds (P < .05). On the ischemic ears, mean closure time for ATP-vesicles–treated wounds was 15.3 days versus 19.3 days for saline-treated wounds (P < .01). Histological study indicated better healing and re-epithelialization in the ATP-vesicles–treated wounds.

Conclusions

Intracellular delivery of ATP accelerated the healing process of diabetic skin wounds on ischemic and non-ischemic rabbit ears. The mechanisms deserve further study but may be related to improved cellular energy supplies.

Section snippets

Preparation of ATP-vesicles

The ATP-vesicles were made by Avanti Polar Lipids, Inc. (Alabaster, AL). The freeze-dried ATP-vesicles were stored in a freezer at −20°C. They were mixed with a nonionic vanishing cream (Dermovan, San Antonio, TX) just before use. After reconstitution, the composition was 100 mg/mL of soy PC/DOTAP (Avanti Polar Lipids, Alabaster, AL) (50:1), trehalose/soy PC (2:1), 10 mmol/L of KH2PO4, and 10 mmol/L of Mg–ATP. The diameters of the lipid vesicles ranged from 120 nm to 160 nm, which were measured

Results

There was no death, bleeding, or incisional infection in these animals. Among the 8 rabbits (64 wounds) that were monitored until all wounds were healed, 2 wounds (1 treated by ATP-vesicles and 1 treated by saline) on the ischemic ear in 1 rabbit were infected. These 2 wounds healed extremely slowly, and were excluded from wound healing time analysis. The remaining 62 wounds were used for healing comparison.

Comments

The important findings of this experiment include the following: (1) wound experiment can be performed successfully in rabbits with the combination of diabetes, ischemia, and nerve damage; (2) the delivery of ATP into the cell can accelerate the healing process of ischemic and non-ischemic skin wounds in diabetic rabbits; (3) the extremely rapid granulation tissue growth in the diabetic animals in this study is something never seen or reported in humans or any other land animals in the past;

Acknowledgments

This publication was made possible in part by Grant No. DK74566 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and AR52984 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). We thank Sheron Lear in the Special Procedures Laboratory for her sample preparations for histological study.

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    Sufan Chien is the partner of Novera, LLC in Louisville, which plans to further develop and commercialize the ATP-vesicle for wound treatment.

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