Pigmentation Diathesis of Hypertrophic Scar: An Examination of Known Signaling Pathways to Elucidate the Molecular Pathophysiology of Injury-Related Dyschromia.

Hypertrophic scar (HTS) occurs frequently after burn injury. Treatments for some aspects of scar morbidity exist, however, dyspigmentation treatments are lacking due to limited knowledge about why scars display dyschromic phenotypes. Full thickness wounds were created on duroc pigs that healed to form dyschromic HTS. HTS biopsies and primary cell cultures were then used to study pigmentation signaling. Biopsies of areas of both pigment types were taken for analysis. At the end of the experiment, melanocyte-keratinocyte cocultures were established from areas of differential pigmentation. Heterogeneously dyspigmented scars formed with regions of hyperpigmentation and hypopigmentation. Melanocytes were present in both pigment types measured by S100ß quantitative real time-polymerase chain reaction (qRT-PCR) and immunostaining, and visualized by dendritic cell presence in primary cultures. P53 expression was not different between the two pigment types. Hyperpigmented scars had upregulated levels of proopiomelanocortin (POMC), adrenocorticotropic hormone (ACTH), α-melanocyte stimulating hormone (α-MSH), stem cell factor (SCF), and c-KIT and melanocortin 1 receptors (MC1R) compared to hypopigmented regions. Many genes involved in dyspigmentation were differentially regulated by microarray analysis including MITF, TYR, TYRP1, and DCT. MiTF expression was not different upon further exploration, but TYR, TYRP1, and DCT were upregulated in intact biopsies measured by qRT-PCR and confirmed by immunostaining. This is the first work to confirm the presence of melanocytes in hypopigmented scar using qRT-PCR and primary cell culture. An understanding of the initial steps in dyspigmentation signaling, as well as the downstream effects of these signals, will inform treatment options for patients with scars and provide insight to where pharmacotherapy may be directed.

Plasma Ameliorates Endothelial Dysfunction in Burn Injury.

BACKGROUND: A complex inflammatory response mediates the systemic effects of burn shock. Disruption of the endothelial glycocalyx causes shedding of structural glycoproteins, primarily syndecan-1 (SDC-1), leading to endothelial dysfunction. These effects may be mitigated by resuscitative interventions. MATERIALS AND METHODS: Sprague-Dawley rats were used to create small, medium, and large burns and uninjured controls. Three different intravenous resuscitation protocols were applied within each group: Lactated Ringer's (LR) alone, LR plus fresh frozen plasma (FFP), or LR plus albumin. Blood was serially collected, and plasma SDC-1 was quantified with enzyme-linked immunosorbent assay. In one cohort, Evan's Blue Dye (EBD) was administered and quantified in lung by spectrophotometry as a functional assay of vascular permeability. In a second cohort, intact SCD-1 was quantified by immunohistochemistry in lung tissue. Statistical analysis employed two-way analysis of variance with multiple comparisons and Student's t-test. RESULTS: EBD extraction from lung was significantly greater with higher injury severity versus controls. Extraction decreased significantly in large-burn animals with addition of FFP to LR versus LR-only; addition of albumin to LR did not decrease EBD extraction. Plasma SCD-1 increased in injured animals compared with controls, and changes correlated with injury severity in all resuscitation groups (significance, P < 0.05). Lung SCD-1 staining reflected the results in the EBD assay. CONCLUSIONS: Addition of FFP, not of albumin, to post-burn resuscitation diminishes vascular leakage associated with large burns. Addition of colloid does not affect SDC-1 shedding as measured in plasma. Ongoing work will further define pathophysiologic mechanisms and potential therapeutic interventions to mitigate injury and promote repair of the endothelial glycocalyx.

Reference ranges for rotational thromboelastometry in male Sprague Dawley rats.

BACKGROUND: A functional coagulation assay was used to investigate the extrinsic pathway of coagulation on citrated whole blood samples from healthy adult male Sprague Dawley rats using the mini cup and pin system. METHODS: Reference values for coagulation parameters from forty-three animals were calculated using data obtained from the ROTEM® delta hemostasis analyzer with the EXTEM test. RESULTS: The following ranges, presented as the 2.5-97.5 percentiles, were established: CT [18-77], CFT [20-80], α [73-86], MCF [53-70], and ML [1-22], along with others. CONCLUSIONS: These reference ranges can be used in future studies in rats to identify clinically significant coagulopathies.