Sterile Injury Repair and Adhesion Formation at Serosal Surfaces

Most multicellular organisms have a major body cavity containing vital organs. This cavity is lined by a mucosa-like serosal surface and filled with serous fluid which suspends many immune cells. Injuries affecting the major body cavity are potentially life-threatening. Here we summarize evidence that unique damage detection and repair mechanisms have evolved to ensure immediate and swift repair of injuries at serosal surfaces. Furthermore, thousands of patients undergo surgery within the abdominal and thoracic cavities each day. While these surgeries are potentially lifesaving, some patients will suffer complications due to inappropriate scar formation when wound healing at serosal surfaces defects. These scars called adhesions cause profound challenges for health care systems and patients. Therefore, reviewing the mechanisms of wound repair at serosal surfaces is of clinical importance. Serosal surfaces will be introduced with a short embryological and microanatomical perspective followed by a discussion of the mechanisms of damage recognition and initiation of sterile inflammation at serosal surfaces. Distinct immune cells populations are free floating within the coelomic (peritoneal) cavity and contribute towards damage recognition and initiation of wound repair. We will highlight the emerging role of resident cavity GATA6+ macrophages in repairing serosal injuries and compare serosal (mesothelial) injuries with injuries to the blood vessel walls. This allows to draw some parallels such as the critical role of the mesothelium in regulating fibrin deposition and how peritoneal macrophages can aggregate in a platelet-like fashion in response to sterile injury. Then, we discuss how serosal wound healing can go wrong, causing adhesions. The current pathogenetic understanding of and potential future therapeutic avenues against adhesions are discussed.

DISPOSABLE SYSTEM FOR IN-VIVO MECHANICAL CHARACTERIZATION OF SOFT TISSUES BASED ON VOLUME MEASUREMENT

In-vivo characterization of soft tissues is a key step toward biomechanical simulation and planning of intra-operative assisted surgery. To achieve this, aspiration method is a standard technique: tissue is aspirated through a hole while measuring the pressure and associated apex height. An inverse problem is then solved to identify the material mechanical properties. In the literature, the apex height is usually measured using a camera, which induces design difficulties, in particular in regards on the required sterilization process for in-vivo measurements. In this paper, the idea is to replace the apex height optical measurement by the measurement of the aspirated tissue volume. The proposed method enables to reduce the system head to a simple tube: sterilizations becomes easy and the system is disposable after use. The proposed system is thus the simplest, lightest and cheapest one could achieve. It is also to the authors knowledge the first time ever in aspiration method that the aspired volume is the extracted data. As the data signal-to-noise ratio is the main factor impacting any applied inverse method when extracting the mechanical properties, the aim of this work is to assess and compare the experimental signal-to-noise ratio in the raw volume measurements obtained either optically or with the method proposed. Explicit results of inverse methods using volumes as input data are not presented in this paper for concision purpose. The effects on accuracy of various experimental parameters has been investigated and quantified: the volume measurement has proved to present a same order or even better signal-to-noise ratio compared to optical measurements.

Cervical softening occurs early in pregnancy: characterization of cervical stiffness in 100 healthy women using the aspiration technique

OBJECTIVE

To quantitatively describe the evolution of ectocervical stiffness in normal pregnancy.

METHODS

The stiffness of ectocervical tissue was measured by using the aspiration method. This non-invasive technique allows to safely and objectively determine the pressure required to displace cervical tissue to a predefined deformation level (pcl ). In this prospective study, 448 aspiration measurements were carried out on pregnant women (n = 50) at each of the eight routine pregnancy consultations and on nonpregnant subjects (reference, n = 50). pcl values were grouped as nonpregnant, first, second, third trimester, and postpartum.

RESULTS

Stiffness in early pregnancy (first trimester) is significantly lower, by a factor >2 for the mean value than for the nonpregnant group. pcl continuously decreases during gestation, with significant differences between first and second trimester, but not between second and third trimester. After delivery, consistency is recovered to the level of early pregnancy.

CONCLUSIONS

The aspiration method allows an objective description of the consistency of the ectocervix during pregnancy, indicating that the tissue softens already at the beginning of gestation, transforms continuously to lower consistency in the first two trimesters, stabilizes at a low level in the third trimester, and recovers its stiffness after delivery.