363 Examination of Differences in Hypertrophic Scar Potential of Large, Full Thickness Wounds in Yorkshire Versus Duroc Swine
Bibliographic record
Abstract
Wound healing is a complex process with various outcomes, including repair back to normal skin, hypertrophic scar (HTS) and dyspigmented scar. Pigs serve as in vivo models to study wound healing as their skin shares many physiological similarities with humans. Two common models are Yorkshire (Yk) and Duroc (Dc) pigs. Yk pigs have been used to mimic normal wound healing while Dc pigs demonstrate abnormal wound healing (HTS/dyspigmented scar). The reason for this differential healing phenotype has not been extensively explored. Our goal was to examine if the same differences in healing held true in 16 square inch wounds. Full thickness excisional wounds (4x4 in) were made on the bilateral flanks of Dc and Yk pigs (n=8 scars each). Wounds were sampled and imaged weekly until 42 days post injury and then biweekly until day 98. At each check, an occupational therapist calculated a Vancouver Scar Scale (VSS) score. Re-epithelialization was analyzed using Image J software. H & E and Mason’s Trichrome stains were used to determine cellularity and collagen content of wound and scar tissue. Immunostaining for α-smooth muscle actin was used to determine blood vessel density in tissue. Normal Yk skin has a white phenotype that resembles Caucasian skin. It heals to a “port wine” HTS. Normal Dc skin has a red/brown phenotype that more closely resembles African American skin that heals to a dyspigmented, non-pliable HTS. Yk scars had a higher VSS score at all time points (n=8, p < 0.03). Yk wounds had a higher % re-epithelialization than Dc wounds at days 7, 14, 21, and 28, thus, these wounds closed faster. Tissue cellularity increased from baseline in both species at day 7 (n=8, p < 0.0002). In Yk tissue, cellularity was slightly above baseline at day 98, while Dc tissue remained more cellular than its baseline (p < 0.05). At day 98, Yk and Dc scars returned to similar collagen levels as healthy skin, although collagen disorganization was observed in both scars. Yk scar had increased blood vessel density at day 56. This is the first work to show the outcomes of a full thickness excisional wound of this size on Yk pigs. The higher VSS score of Yk scar is mostly due to a higher vascularity score. Increased Yk scar blood vessel density at day 56 supports this finding. However, it is unexplained why Yk scar tissue begins to return to normal cellularity levels while Dc remains escalated. These results suggest that there is a vast difference in how skin of differential pigmentation heals. Moving forward, when using an in vivo model to investigate new therapeutic treatments, it will be useful to include both pig types. This will provide insight into a treatment’s effectiveness on varying skin types.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".