Porcine Acute Wound Healing
Duration of study - Typically 14 to 28 days
Lead time – 30 days
Standard results – Wound size measurements, Wound Evaluations, Photography, Histology
Model Utility:
This wound healing model is used to screen wound healing agents and medical devices for effectiveness.
How the Model Works:
In this model, full thickness excisional wounds are made on the dorsal thorax of the animal. The size and number of wounds created can vary based on the needs of the experiment; however, the standard number and size of wounds are 20, 2.0 cm diameter wounds per animal. The wounds may then be treated with the experimental agent or medical device. These can be in the form of a liquid, gel, powder, or solid (typically cut to wound size). The wounds will then be bandaged with an appropriate bandage for the type of material used and allowed to heal for typically 14 to 28 days. The wounds will be measured and/or assessed twice per week. Treatments may be applied as often as once per day.
At the end of the protocol, the animal is euthanized, and the wounded area is collected for histological or other analysis.
Example Data:
Figure 1. A comparison of total wound area as a percentage of Day 0 wound area. Two test materials were compared to a predicate material.
Figure 2. A retrospective analysis of 295 untreated, control wounds from 9 studies over 6 years. The data very closely approximates a typical healing curve with the slow “Inflammatory” phase followed by the rapid “Regenerative” phase and the “Remodeling” tail-end clearly discernible. Three linear regression lines have been included – one representing the period from Day 0 to Day 4 (Blue), demonstrating the Inflammatory phase, one representing the period from Day 4 to Day 14 (Orange), demonstrating the Re-epithelialization phase, and the third representing the period from Day 14 to Day 24 (Green), demonstrating the Remodeling phase of healing.
Advantages:
This model is considered to very closely approximate human wound healing. BRIDGE PTS is very familiar with this model. Due to the spacing of the wound on the animal, multiple test materials can be tested on a single animal. This could allow for higher throughput screening.
This model can also be performed with infection! See Pig Infected Wound Healing.
Disadvantages:
If multiple test materials are placed on a single animal, it is difficult or impossible to assess systemic effects that the materials may have.
References
Wright JB, Lam K, Buret AG, Olson ME, Burrell RE. Early healing events in a porcine model of contaminated wounds: effects of nanocrystalline silver on matrix metalloproteinases, cell apoptosis, and healing. Wound Repair Regen. 2002 May-Jun;10(3):141-51
Olson ME, Wright JB, Lam K, Burrell RE. Healing of porcine donor sites covered with silver-coated dressings. Eur J Surg. 2000 Jun;166(6):486-9.