Tchoukalova, Yourka D.

Comparative analysis of fibrin sealant and recombinant thrombin hydrogels reveals distinct microarchitectures and cellular responses, emphasizing recombinant thrombin’s potential to enhance cellular activity and enable vesicle delivery.

Objectives: Gain insights into the pathophysiology of idiopathic subglottic stenosis (iSGS) by investigating differences in transcriptome of subglottic mucosal tissue between patients with iSGS and controls, and between tracheal and subglottic tissue within patients. Methods: RNA sequencing was conducted on biopsied mucosal samples collected from subglottic and tracheal (in-patient control) regions in iSGS patients, and from subglottis in controls. The gene expression differences were validated on a protein level by (1) staining the tissue samples obtained from a second cohort of patients and controls; and (2) in vitro functional assays using primary subglottic epithelial cells from both iSGS patients and healthy donors. Results: We found 7 upregulated genes in the subglottic region of iSGS patients relative to both the tracheal mucosa and subglottic region of controls. A gene ontology enrichment analysis found that the epithelial cell differentiation and cornification pathways are significant, involving specifically 3 of the genes: involucrin ( IVL), small proline rich protein 1B ( SPRR1B), and keratin 16 ( KRT16). Involvement of these pathways suggests squamous metaplasia of the epithelium. Histological analyses of epithelium in subglottic mucosal biopsies revealed squamous metaplasia in 41% of the samples from iSGS patients and in 25% from controls. Immunohistochemical evaluation of the samples presented with squamous epithelium revealed increased expression of the protein encoded by SPRR1B, hyperproliferative basal cells, shedding of apical layers, and accompanying lesions in iSGS compared to CTRL. Cultured primary subglottic epithelial cells from iSGS patients had higher proliferation rates compared to healthy donors and squamous metaplastic differentiation formed thinner epithelia with increased expression proteins encoded by INV, SPRR1B, and KRT16, suggesting intrinsic dysfunction of basal cells in iSGS. Conclusions: Abnormal squamous differentiation of epithelial cells may contribute to the pathogenesis of iSGS. Patients having metaplastic epithelial phenotype may be sensitive to drugs that reverse it to a normal phenotype.

AbstractPelvic organ prolapse (POP) is a dysfunction that affects a large proportion of women. Current support scaffolds’ lack of biocompatibility, biodegradability, and mechanical compliance are associated with surgical complications including erosion and pain, indicating the urgent need for new tissue scaffolds with customizable functions. A new material that uses polyvinyl alcohol (PVA) as the main ingredient and is chemically tuned to possess suitable mechanical properties and degradation rates for the surgical treatment of POP is developed. Specifically, the thiol‐norbornene “click” chemistry enables the sol‐gel transition of the biomaterial under UV‐light without side‐products. Meanwhile, NaOH treatment further toughens the hydrogel with a higher crosslink density. The PVA‐based biocompatible ink can be printed with UV‐facilitated direct ink writing due to the rapidly UV‐initiated chemical crosslink; in situ image analysis and machine learning methods are applied during this procedure to quantify and improve the printing quality. The cell viability results demonstrate the biocompatibility of the POP scaffolds, suggesting the potential for future animal studies and the possibility of clinical research. This study bridges polymer chemistry and manufacturing engineering with a specific tissue engineering application to solve the common disorder of POP, shedding light on individualized medicine and intelligent systems for biomedical engineering.

AbstractThere are reciprocal interactions between epithelial cells and underlying basement membrane. The resemblance of biomaterials to native basement membrane is thus critical for their success when used to regenerate epithelium‐containing organs. Particularly, the use of nanofibers and the incorporation of basement membrane proteins may mimic both biophysical and biochemical properties of basement membrane, respectively. Herein we tested how electrospun polycaprolactone/heparin fibers with and without adsorbed laminin and collagen IV proteins affect epithelial cell functions. We found that airway epithelial cells attached, migrated, and proliferated on all scaffolds but protein‐functionalized fibers promoted higher attachment, quicker migration, and increased proliferation. Fibers were then integrated on polyethylene scaffolds and cultured at an air‐liquid interface. The detection of secretory and ciliated cell markers was higher in cells on polyethylene with fibers. These findings demonstrate that electrospun fibers incite beneficial epithelial cell responses and can be used in the fabrication of bioengineered functional epithelia.

Objectives/HypothesisDevelop a patient‐specific tissue engineered construct for laryngeal reconstruction following a partial laryngectomy.Study DesignBench and animal research.MethodsA construct made from a porous polyethylene scaffold shaped in a canine‐specific configuration and seeded with autologous canine adipose‐derived stem cells in fibrin glue was implanted in a canine following a partial laryngectomy. After 1 year, the construct was first evaluated in vivo with high‐speed imaging and acoustic–aerodynamic measures. It was then explanted and evaluated histologically.ResultsThe canine study at 1 year revealed the construct provided voicing (barking) with acoustic and aerodynamic measures within normal ranges. The canine was able to eat and breathe normally without long‐term support. The construct was integrated with epithelialization of all areas except the medial portion of the vocal fold structure. No anti‐infective agents were needed after the standard perioperative medications were completed.ConclusionThis study provided a successful first step toward developing a patient‐specific composite construct for patients undergoing partial laryngectomies.Level of EvidenceNA Laryngoscope, 132:S1–S11, 2022

Women differ from men by the larger lower‐body subcutaneous fat mass and the tendency to gain more fat in that depot if obesity develops. We hypothesized that these differences in fat distribution may depend on preadipocyte availability. We identified the proportion of preadipocytes from the stromovascular (SV) cells in adipose tissue by immunofluorescent staining for aP2 (the adipocyte fatty acid trafficking protein) and CD68 (a macrophage marker). Macrophages are the other cell type, aside from preadipocytes, in the SV fraction of adipose tissue that express aP2. We determined the percent preadipocytes in the SV fraction of subcutaneous abdominal and femoral adipose tissue of 17 premenopausal lean women and 10 age‐matched lean men. Body fat compartments were measured by DEXA and CT scans of the abdomen. Compared to men, women had less visceral fat and more subcutaneous fat mass, predominantly in the lower‐body compartment: 7.0 ± 0.3 kg vs. 5.2 ± 0.4 kg, respectively (p < 0.01). Femoral adipocytes were significantly larger than abdominal adipocytes in both groups (lipid per fat cell in women and men: abdomen, 0.46 ± 0.03 and 0.44 ± 0.06 μg/cell; thigh, 0.66 ± 0.04 and 0.55 ± 0.08 μg/cell, respectively). The percent preadipocytes in the SV fraction from femoral subcutaneous adipose tissue was greater in women than in men (29.7 ± 2.6% vs. 19.3 ± 2.0%, p < 0.02) but similar when isolated from the abdominal depot (29.9 ± 3.3% vs. 27.2 ± 1.9%). Our findings suggest that the fraction of femoral stromovascular cells as preadipocytes is a potential factor for sex‐dependent differences in regional fat distribution. The study was funded by RO1 DK 45343‐13S to M. Jensen.

ObjectiveThe study aims to demonstrate the reproducibility and feasibility of creating a hemilaryngeal model with a medialized vocal fold (VF) using 3‐dimensional (3D) modeling techniques in both healthy larynges and those affected by cancer.Study DesignThree‐dimensional modeling of human larynges.SettingTertiary academic referral center and regenerative medicine laboratory.Subjects and MethodsComputed tomography (CT) scans from 10 healthy control and 10 patients with laryngeal cancer were segmented and imported into 3D modeling software. The larynx was cut sagittally to create a hemilaryngeal model and the vocal fold medialized. Measurements were taken from the CT and 3D model data and compared.ResultsAll control modeling data closely matched the CT data and were not statistically different from each other. There was a significant correlation between subglottic anteroposterior diameter and VF length (r2 = 0.78, P =. 0008), and it may be a valuable tool to infer true VF dimension in cases where disruption has occurred. The modeling data from patients with cancer did not show statistical difference to the control data, showing that accurate modeling can also be achieved in patients with laryngeal cancer.ConclusionCT scan‐based 3D modeling of the larynx and VF is possible and reproducible. The results closely match those previously reported in the literature and can also be replicated in cases with laryngeal cancer. This study paves the way for future de novo fabricated laryngeal scaffolds that can be synthesized using 3D printers and tailored to meet surgical demands.

Introduction: The purpose of this study was to compare different decellularization protocols with the conventional detergent enzymatic method (DEM) using continuous agitation. Methods: The first experiment compared conventional DEM with sonication and lyophilization+freeze-thaw cycles. A second experiment was carried out to compare time-adjusted DEM (2-hour instead of 4-hour incubations with 4% deoxycholate) to decellularization in a bioreactor. Cellularity was determined by DNA-quantitation, H&E-staining and immunostaining for major histocompatibility complex-1 (MHC-1). Results: Compared to untreated trachea, DNA content significantly decreased after 2 cycles in all groups in the first experiment and dropped below the minimal criteria for efficient decellularization (<50 ng dsDNA/mg dry weight) after 4 cycles. However, nuclei were seen in the cartilage and MCH-1 staining was detected in some submucosal areas, indicating presence of chondrocytes and cellular residues that may render the scaffold immunogenic. In the second experiment DNA content significantly decreased after 1 cycle in both groups; however, even after 4 cycles, DNA content was above the minimal criteria for efficient decellularization. While collagen-levels remained stable, glycosaminoglycans diminished significantly after the initial cycles. Conclusions: Efficient decellularization can be achieved after only 4 cycles of DEM compared to the 17 cycles previously reported. The use of a bioreactor can preserve the integrity of the extracellular matrix.

This review aims to summarize contemporary evidence of the in vitro and in vivo immunomodulatory effects of mesenchymal stem cells (MSCs) in promoting vascularized composite allotransplant (VCA) tolerance. An extensive literature review was performed to identify pertinent articles of merit. Prospective preclinical trials in mammal subjects receiving VCA (or skin allograft) with administration of MSCs were reviewed. Prospective clinical trials with intravascular delivery of MSCs in human populations undergoing solid organ transplant were also identified and reviewed. Sixteen preclinical studies are included. Eleven studies compared MSC monotherapy to no therapy; of these, ten reported improved graft survival, which was statistically significantly prolonged in eight. Eight studies analyzed allograft survival with MSC therapy as an adjunct to proven immunosuppressive regimens. In these studies, daily immunosuppression was transiently delivered and then stopped. In all studies, treatment-free graft survival was statistically significantly prolonged in animals that received MSC therapy. MSCs have been safely administered clinically and their use in renal transplant clinical trials provides evidence that they improve allograft transplant tolerance in clinical practice. There is potential for MSC induction therapy to overcome many of the obstacles to widespread VCA in clinical practice. Preclinical studies are needed before MSC-induced VCA tolerance becomes a clinical reality.

Fat distribution varies among individuals with similar body fat content. Innate differences in adipose cell characteristics may contribute because lipid accumulation and lipogenic enzyme activities vary among preadipocytes cultured from different fat depots. We determined expression of the adipogenic transcription factors peroxisome proliferator activated receptor-γ (PPAR-γ) and CCAAT/enhancer binding protein-α (C/EBP-α) and their targets in abdominal subcutaneous, mesenteric, and omental preadipocytes cultured in parallel from obese subjects. Subcutaneous preadipocytes, which had the highest lipid accumulation, glycerol-3-phosphate dehydrogenase (G3PD) activity, and adipocyte fatty acid binding protein (aP2) abundance, had highest PPAR-γ and C/EBP-α expression. Levels were intermediate in mesenteric and lowest in omental preadipocytes. Overexpression of C/EBP-α in transfected omental preadipocytes enhanced differentiation. The proportion of differentiated cells in colonies derived from single subcutaneous preadipocytes was higher than in mesenteric or omental clones. Only cells that acquired lipid inclusions exhibited C/EBP-α upregulation, irrespective of depot origin. Thus regional variation in adipogenesis depends on differences at the level of transcription factor expression and is a trait conferred on daughter cells.