Three-dimensional Printing in the Intestine.

Intestinal transplantation remains a life-saving option for patients with severe intestinal failure. With the advent of advanced tissue engineering techniques, great strides have been made toward manufacturing replacement tissues and organs, including the intestine, which aim to avoid transplant-related complications. The current paradigm is to seed a biocompatible support material (scaffold) with a desired cell population to generate viable replacement tissue. Although this technique has now been extended by the three-dimensional (3D) printing of geometrically complex scaffolds, the overall approach is hindered by relatively slow turnover and negative effects of residual scaffold material, which affects final clinical outcome. Methods recently developed for scaffold-free 3D bioprinting may overcome such obstacles and should allow for rapid manufacture and deployment of "bioprinted organs." Much work remains before 3D bioprinted tissues can enter clinical use. In this brief review we examine the present state and future perspectives of this nascent technology before full clinical implementation.

Aptamer-targeted antigen delivery.

Effective therapeutic vaccines often require activation of T cell-mediated immunity. Robust T cell activation, including CD8 T cell responses, can be achieved using antibodies or antibody fragments to direct antigens of interest to professional antigen presenting cells. This approach represents an important advance in enhancing vaccine efficacy. Nucleic acid aptamers present a promising alternative to protein-based targeting approaches. We have selected aptamers that specifically bind the murine receptor, DEC205, a C-type lectin expressed predominantly on the surface of CD8α(+) dendritic cells (DCs) that has been shown to be efficient at facilitating antigen crosspresentation and subsequent CD8(+) T cell activation. Using a minimized aptamer conjugated to the model antigen ovalbumin (OVA), DEC205-targeted antigen crosspresentation was verified in vitro and in vivo by proliferation and cytokine production by primary murine CD8(+) T cells expressing a T cell receptor specific for the major histocompatibility complex (MHC) I-restricted OVA257-264 peptide SIINFEKL. Compared with a nonspecific ribonucleic acid (RNA) of similar length, DEC205 aptamer-OVA-mediated antigen delivery stimulated strong proliferation and production of interferon (IFN)-γ and interleukin (IL)-2. The immune responses elicited by aptamer-OVA conjugates were sufficient to inhibit the growth of established OVA-expressing B16 tumor cells. Our results demonstrate a new application of aptamer technology for the development of effective T cell-mediated vaccines.

Hydrogel-based 3D bioprints repair rat small intestine injuries and integrate into native intestinal tissue.

3D Printing has become a mainstay of industry, with several applications in the medical field. One area that could benefit from 3D printing is intestinal failure due to injury or genetic malformations. We bioprinted cylindrical tubes from rat vascular cells that were sized to form biopatches. 2 mm enterotomies were made in the small intestine of male Sprague-Dawley rats, and sealed with biopatches. These intestinal segments were connected to an ex vivo perfusion device that provided independent extraluminal and intraluminal perfusion. The fluorescence signal of fluorescein isothiocyanate (FITC)-inulin in the intraluminal perfusate, a non-absorbable fluorescent marker of intestinal integrity, was measured every 15 min over 90 min, and used to assess the integrity of the segments under both continuous perfusion and alternate-flow perfusion. Enterotomies were made an inch away from the ileocecal junction in male Wistar rats and sealed with biopatches. The animals were monitored daily and euthanized at post-operative days 7, 14, 21, and 30. Blinded histopathological analysis was conducted to compare the patch segments to native intestine. Biopatch-sealed intestinal segments withstood both continuous and pulsatile flow rates without leakage of FITC-inulin above the control baseline. 21 of 26 animals survived with normal activity, weight gain, and stool output. Histopathology of the explanted segments showed progressive villi and crypt formation over the enterotomies, with complete restoration of the epithelium by 30 days. This study presents a novel application of 3D bioprinting to develop a universal repair patch that can seal lesions in vivo, and fully integrate into the native intestine.

Rothman Index variability predicts clinical deterioration and rapid response activation.

BACKGROUND: The overall utility of the Rothman Index (RI), a global measure of inpatient acuity, for surgical patients is unclear. We evaluate whether RI variability can predict rapid response team (RRT) activation in surgical patients. METHODS: Surgical patients who underwent RRT activation from 2013 to 2015 were matched to four control cases. RI variability was gauged by maximum minus minimum RI (MMRI) and RI standard deviation (RISD) within a 24-h period before RRT. The primary outcome measured was RRT activation, and our secondary outcome was in-hospital mortality. RESULTS: Two hundred seventeen (217) patients underwent RRT. RISD (odds ratio, OR, 1.31, 95% confidence interval, CI, 1.23-1.38, P < 0.001; area under receiver operating characteristic, AUROC, curve 0.74, 95% CI 0.70-0.77) and MMRI (OR 1.10, 95% CI 1.08-1.12, P < 0.001; AUROC 0.76, 95% CI 0.72-0.79) predicted increased likelihood of RRT. CONCLUSIONS: RISD is predictive of RRT.

Overutilization of Cross-Sectional Imaging in the Lower Extremity Trauma Setting.

Objective In an era of managed care and cost savings, we are faced with the question of whether another test is necessary to confirm our clinical suspicion. We hypothesized that a few computed tomography angiographies (CTAs) are necessary to identify lower extremity vascular injuries (LEVIs). We reviewed our trauma center's experience in the management of LEVI. Methods A retrospective review of all trauma patients between 2012 and 2016 was performed. Four-thousand nine-hundred fourteen trauma patients were evaluated with 46 suspected LEVIs (either with cross-sectional imaging and/or operative exploration). Our primary end point was the utility of CTA in the setting of LEVI. Receiver operating characteristic curves were performed to evaluate sensitivity and specificity for hard signs and CTA identification of LEVI. Results Out of the initial 46 patients with suspected LEVI, 41 (89%) had a CTA as part of their initial evaluation. Sixteen patients (35%) with LEVI were due to penetrating injuries. Seventeen patients (41%) had a CTA with LEVI. Fourteen of the 17 patients (82%) with injury on CTA also had hard signs of LEVI. Twenty-two patients (48%) underwent operative exploration: three had no LEVI that was previously believed to be on CTA; operative exploration identified two missed injuries not observed on CTA. Seven of forty-one (17%) CTA studies provided a false assumption of the presence/absence of LEVI. One patient (2%) underwent operative exploration and was found to have LEVI in the absence of hard signs, but with a CTA identifying LEVI. Conclusion The recognition of hard signs through physical examination is paramount to assessing need for operative intervention with suspicion of LEVI. CTA should be reserved as an adjunct for identification of LEVI in patients with high clinical suspicion and absence of hard signs, rather than utilizing CTA as an initial screening tool for the identification of LEVI.

An RNA alternative to human transferrin: a new tool for targeting human cells.

The transferrin receptor, CD71, is an attractive target for drug development because of its high expression on a number of cancer cell lines and the blood brain barrier. To generate serum-stabilized aptamers that recognize the human transferrin receptor, we have modified the traditional aptamer selection protocol by employing a functional selection step that enriches for RNA molecules which bind the target receptor and are internalized by cells. Selected aptamers were specific for the human receptor, rapidly endocytosed by cells and shared a common core structure. A minimized variant was found to compete with the natural ligand, transferrin, for receptor binding and cell uptake, but performed ~twofold better than it in competition experiments. Using this molecule, we generated aptamer-targeted siRNA-laden liposomes. Aptamer targeting enhanced both uptake and target gene knockdown in cells grown in culture when compared to nonmodified or nontargeted liposomes. The aptamer should prove useful as a surrogate for transferrin in many applications including cell imaging and targeted drug delivery.