A technique for repeated blood and cerebrospinal fluid sampling from individual rats over time without the need for repeated anesthesia.

Ethical animal use follows the 3R's: Replacement, Reduction and Refinement. Here, we present the use of simultaneous jugular vein and cisterna magna catheterization via a port system in rats for repeated fluid sampling for 14 consecutive days without loss of catheter patency. This technique allows repeated intra-animal sampling without anesthesia and, if used with pooling samples from a cohort of animals, replaces the need for terminal collections for sufficient sample volumes.

The pig as a model system for investigating the recruitment and contribution of myofibroblasts in skin healing.

In the skin-healing field, porcine models are regarded as a useful analogue for human skin due to their numerous anatomical and physiological similarities. Despite the widespread use of porcine models in skin healing studies, the initial origin, recruitment and transition of fibroblasts to matrix-secreting contractile myofibroblasts are not well defined for this model. In this review, we discuss the merit of the pig as an animal for studying myofibroblast origin, as well as the challenges associated with assessing their contributions to skin healing. Although a variety of wound types (incisional, partial thickness, full thickness, burns) have been investigated in pigs in attempts to mimic diverse injuries in humans, direct comparison of human healing profiles with regards to myofibroblasts shows evident differences. Following injury in porcine models, which often employ juvenile animals, myofibroblasts are described in the developing granulation tissue at 4 days, peaking at Days 7-14, and persisting at 60 days post-wounding, although variations are evident depending on the specific pig breed. In human wounds, the presence of myofibroblasts is variable and does not correlate with the age of the wound or clinical contraction. Our comparison of porcine myofibroblast-mediated healing processes with those in humans suggests that further validation of the pig model is essential. Moreover, we identify several limitations evident in experimental design that need to be better controlled, and standardisation of methodologies would be beneficial for the comparison and interpretation of results. In particular, we discuss anatomical location of the wounds, their size and depth, as well as the healing microenvironment (wet vs. moist vs. dry) in pigs and how this could influence myofibroblast recruitment. In summary, although a widespread model used in the skin healing field, further research is required to validate pigs as a useful analogue for human healing with regards to myofibroblasts.

Surfactant protein-A reduces translocation of mediators from the lung into the circulation.

The objective of this study was to characterize a mouse model of lung inflammation and determine the effect of surfactant protein A (SP-A, or sftpa) on the transfer of inflammatory mediators from these injured lungs into the systemic circulation. Lung inflammation was induced in either sftpa-deficient (-/-) or wild-type (+/+) spontaneously breathing, adult mice via intranasal lipopolysaccharide (LPS). Four hours later, lungs were isolated, perfused, and mechanically ventilated for 2 hours. Perfusate was collected for analysis over the duration of ventilation and lung lavage was obtained in groups of animals immediately before and after mechanical ventilation (MV). Lavage analysis showed an increase in interleukin-6 (IL6) and tumor necrosis factor-alpha (TNFalpha) 4 hours after LPS, with a further increase in IL6 following MV. LPS and MV also caused an increase in total cell and neutrophil numbers as well as total protein in the lavage compared to controls. Perfusate analysis revealed a significant increase in IL6 and TNFalpha after LPS and MV, with significantly greater levels of these mediators in sftpa (-/-) versus (+/+) mice. The authors conclude that LPS followed by MV resulted in lung inflammation and injury, and that SP-A significantly influenced inflammatory mediator release from these inflamed lungs into the perfusate.

Lung mechanics in the TIMP3 null mouse and its response to mechanical ventilation.

Tissue inhibitor of metalloproteinase-3 (TIMP3) null mice develop emphysema-like airspace enlargement due to an enzymatic imbalance. This study investigates how these abnormalities alter lung mechanics and the response to 2 different mechanical ventilation strategies. Phenotypically, TIMP3 null mice had increased compliance, and decreased resistance, tissue damping, and tissue elastance over wild-type controls. Decreased compliance and increased resistance were observed following the injurious ventilation strategy; however, the TIMP3 null response to both ventilation strategies was similar to wild-type mice. In conclusion, TIMP3 null mice have significant alterations in lung mechanics; however, this does not affect their response to ventilation.