Re-exploration of vertical rectus abdominis myocutaneous flap for vaginal reconstruction: Case report and review of the literature.

The vertical rectus abdominis myocutaneous (VRAM) flap is a versatile and well-established reconstructive technique for many defects created as a result of colorectal and gynecologic extirpation. However, major re-operation in the pelvis following a VRAM flap reconstruction several months later is uncommon, and the safety and integrity of the VRAM flap in this setting has not been described. This case examines VRAM flap preservation during repeat exploratory laparotomy, and a unique view of the VRAM flap during interval exploration. We demonstrate an intact flap after lysis of adhesions with an audible Doppler signal, and maintenance of flap integrity in the postoperative period. This further substantiates its use as a durable rotational flap for perineal tissue defects

Tumescent Injections in Subcutaneous Pig Tissue Disperse Fluids Volumetrically and Maintain Elevated Local Concentrations of Additives for Several Hours, Suggesting a Treatment for Drug Resistant Wounds.

PurposeBolus injection of fluid into subcutaneous tissue results in accumulation of fluid at the injection site. The fluid does not form a pool. Rather, the injection pressure forces the interstitial matrix to expand to accommodate the excess fluid in its volume, and the fluid becomes bound similar to that in a hydrogel. We seek to understand the properties and dynamics of externally tumesced (swollen) subcutaneous tissue as a first step in assessing whether tumescent antibiotic injections into wounds may provide a novel method of treatment.MethodsSubcutaneous injections of saline are performed in live and dead pigs and the physical properties (volume, expansion ratio, residence time, apparent diffusion constant) of the resulting fluid deposits are observed with diffusion-weighted magnetic resonance imaging, computed tomography, and 3D scanning.ResultsSubcutaneous tissue can expand to a few times its initial volume to accommodate the injected fluid, which is dispersed thoroughly throughout the tumescent volume. The fluid spreads to peripheral unexpanded regions over the course of a few minutes, after which it remains in place for several hours. Eventually the circulation absorbs the excess fluid and the tissue returns to its original state.ConclusionsGiven the evidence for dense fluid dispersal and several-hour residence time, a procedure is proposed whereby tumescent antibiotic injections are used to treat drug-resistant skin infections and chronic wounds that extend into the subcutaneous tissue. The procedure has the potential to effectively treat otherwise untreatable wounds by keeping drug concentrations above minimum inhibitory levels for extended lengths of time

Intestinal epithelial replacement by transplantation of cultured murine and human cells into the small intestine.

Adult intestinal epithelial stem cells are a promising resource for treatment of intestinal epithelial disorders that cause intestinal failure and for intestinal tissue engineering. We developed two different animal models to study the implantation of cultured murine and human intestinal epithelial cells in the less differentiated "spheroid" state and the more differentiated "enteroid" state into the denuded small intestine of mice. Engraftment of donor cells could not be achieved while the recipient intestine remained in continuity. However, we were able to demonstrate successful implantation of murine and human epithelial cells when the graft segment was in a bypassed loop of jejunum. Implantation of donor cells occurred in a random fashion in villus and crypt areas. Engraftment was observed in 75% of recipients for murine and 36% of recipients for human cells. Engrafted spheroid cells differentiated into the full complement of intestinal epithelial cells. These findings demonstrate for the first time successful engraftment into the small bowel which is optimized in a bypassed loop surgical model

Development of Functional Microfold (M) Cells from Intestinal Stem Cells in Primary Human Enteroids.

Background & aimsIntestinal microfold (M) cells are specialized epithelial cells that act as gatekeepers of luminal antigens in the intestinal tract. They play a critical role in the intestinal mucosal immune response through transport of viruses, bacteria and other particles and antigens across the epithelium to immune cells within Peyer's patch regions and other mucosal sites. Recent studies in mice have demonstrated that M cells are generated from Lgr5+ intestinal stem cells (ISCs), and that infection with Salmonella enterica serovar Typhimurium increases M cell formation. However, it is not known whether and how these findings apply to primary human small intestinal epithelium propagated in an in vitro setting.MethodsHuman intestinal crypts were grown as monolayers with growth factors and treated with recombinant RANKL, and assessed for mRNA transcripts, immunofluorescence and uptake of microparticles and S. Typhimurium.ResultsFunctional M cells were generated by short-term culture of freshly isolated human intestinal crypts in a dose- and time-dependent fashion. RANKL stimulation of the monolayer cultures caused dramatic induction of the M cell-specific markers, SPIB, and Glycoprotein-2 (GP2) in a process primed by canonical WNT signaling. Confocal microscopy demonstrated a pseudopod phenotype of GP2-positive M cells that preferentially take up microparticles. Furthermore, infection of the M cell-enriched cultures with the M cell-tropic enteric pathogen, S. Typhimurium, led to preferential association of the bacteria with M cells, particularly at lower inoculum sizes. Larger inocula caused rapid induction of M cells.ConclusionsHuman intestinal crypts containing ISCs can be cultured and differentiate into an epithelial layer with functional M cells with characteristic morphological and functional properties. This study is the first to demonstrate that M cells can be induced to form from primary human intestinal epithelium, and that S. Typhimurium preferentially infect these cells in an in vitro setting. We anticipate that this model can be used to generate large numbers of M cells for further functional studies of these key cells of intestinal immune induction and their impact on controlling enteric pathogens and the intestinal microbiome