Introduction: Excessive bleeding in trauma and surgical settings leads to increased operative time, reoperation rates, and overall healthcare costs. A wide range of hemostatic agents have been developed to control bleeding that can vary considerably in type of hemostatic action, ease of application, cost, risk of infection, and dependence on patient coagulation. Microfibrillar collagen-based hemostatic materials (MCH) have yielded beneficial results in a variety of applications. Methods: A new flowable collagen product, containing a modified MCH flour, but in a more convenient flowable delivery system, was evaluated for hemostatic efficacy in preclinical models of solid organ injury and spinal cord exposure. The primary objective of this study was to compare the hemostatic potential and local tissue responses to this novel, flowable collagen-based hemostatic agent to the original flour formulation to confirm that the new method of delivery did not interfere with the hemostatic properties of the MCH flour. Results: When observed visually, the flowable MCH flour mixed with saline (FL) provided more precise application and uniform coverage to injured tissues compared to the dry MCH flour alone (F₀). All of the treatments (FL, F₀, and gauze) exhibited comparable Lewis bleed grade at all three time points evaluated in the capsular resection liver injury model (bleed grade: 1.0– 1.3; p> 0.05 in all cases). FL and F₀ exhibited comparable 100% acute hemostatic efficacy and similar long-term histomorphological properties (up to 120 days) in a capsular resection liver injury in pigs, while gauze resulted in significantly lower rates of acute hemostatic efficacy (8– 42%, p< 0.05 in all cases). In an ovine model of dorsal laminectomy and durotomy, FL and F₀ again exhibited comparable results without any neurological effects. Conclusion: Flowable microfibrillar collagen was shown to yield favorable short- and long-term outcomes in two representative applications where hemostatic efficacy is critical to surgical success.

Background/Objectives: The porcine mammary anatomy is poorly characterized, and structures are difficult to differentiate macroscopically, unlike human mammary tissue. The objective of this exploratory study was to describe the Yucatan porcine breast tissue morphology and identify the basic differences and similarities to human breast tissue. Methods: Samples from an adult, non-parous female Yucatan pig were prepared utilizing various methods: freezing at −80 °F (−26.67 °C) with a thickness of 0.5 cm/post-fixation in formalin; freezing at −20 °F (−6.67 °C) with a thickness of 0.5 cm/post-fixation in formalin; or formalin fixed and incised at ~0.8 cm. A descriptive comparison of the gross and microscopic images of the porcine breast morphology to the previously described human breast anatomy was performed. Results: As examined grossly, frozen sections allowed narrower serial cross-sectioning and better visualization of the structures and relationships. The mammary glands were poorly demarcated with extensive interspersed adipose tissue throughout the periphery. The mammary tissue appeared grossly as pigmented tissue and extended within ~0.5 cm from the skin surface, ~2.0 cm deep (within ~0.5 cm of the deep muscle layer), and ~6.5 cm laterally (centered on a teat). There were a number of similarities between Yucatan porcine and human breast tissue, yet there were several inherent structural differences. In contrast to human mammary tissue, porcine mammary glands consist of more diffuse acinar tissue, less well demarcated by defined fascial, lamellar, and ligamentous structures. Conclusions: The Yucatan porcine mammary morphology and similarities to the human mammary region allow for the use of this animal model to guide those developing relevant technologies or performing local surgical interventions in the preclinical setting.