Collagen Constructs Research Articles

The dual effect of fiber density and matrix stiffness on A549 tumor multicellular migration

The tumor microenvironment features dynamic biomechanical interactions between extracellular matrix physics and tumor progression. Tumor growth compresses the supportive matrix, and the stiffness-gradient guides tumor invasion. From the mechanical perspective, the complexity of the matrix topology involving durotaxis-driven metastasis remains lacking in a comprehensive description. In this study, A549 adenocarcinoma spheroids were exposed to a stiffness-and fiber-adjusted collagen matrix to examine the influence of collective motility. Centrifugated compression on the collagen constructs was adopted to mimic the matrix deformation in response to solid tumor development. Centrifugated compression physically stiffened and condensed collagen constructs simultaneously. Cultured with A549 spheroids for 7 days, compressed collagen constructs disadvantaged spheroid expansion without the effect of tumor proliferation potency but promoted matrix metalloproteinase activity corresponding to softened rigidity. Results suggested that the fibrous structure may counterbalance the matrix stiffness-induced motility.

Issues in the design of tissue-engineered collagen constructs and some approaches to their solution: A review

This review article analyzes modern literature sources on the design of bioinks and tissue-engineered constructs on the basis of soluble forms of collagen, including gelatin. The choice of soluble forms of collagen as a biopolymer basis for bioinks and this type of constructs is determined by their unique biocompatibility, bioresorbability, as well as the presence of adhesive sites (motifs) for binding cells with their subsequent proliferation and organ or tissue maturation. However, the poor mechanical properties of products derived from soluble collagens, rapid biodegradation, tendency to lose the solubility of highly viscous solutions when stored or with pH increase limit their application in tissue engineering. The use of more stable low-viscosity collagen solutions does not enable the creation of dimensionally stable tissue-engineered constructs. It is shown that the introduction of various water-soluble biocompatible polymeric additives into hydrogels on the basis of soluble collagens allows the above-mentioned problems to be solved, as well as providing a means to customize the required characteristics of bioinks and tissue-engineered constructs. The additives that improve their characteristics include biopolymers: silk sericin and fibroin, as well as alginates and fibrinogen, which can form cross-links in the presence of Ca2+. This type of crosslinking is shown to further improve the performance of these constructs. All of these biopolymers are commercially available. The article comparatively analyzes approaches to stabilizing the shape, improving the mechanical properties, and adjusting the bioresorption time of 3D printed tissue-engineered constructs during organ or tissue maturation.

Cellular Imaging and Time-Domain FLIM Studies of Meso-Tetraphenylporphine Disulfonate as a Photosensitising Agent in 2D and 3D Models.

Fluorescence lifetime imaging (FLIM) and confocal fluorescence studies of a porphyrin-based photosensitiser (meso-tetraphenylporphine disulfonate: TPPS2a) were evaluated in 2D monolayer cultures and 3D compressed collagen constructs of a human ovarian cancer cell line (HEY). TPPS2a is known to be an effective model photosensitiser for both Photodynamic Therapy (PDT) and Photochemical Internalisation (PCI). This microspectrofluorimetric study aimed firstly to investigate the uptake and subcellular localisation of TPPS2a, and evaluate the photo-oxidative mechanism using reactive oxygen species (ROS) and lipid peroxidation probes combined with appropriate ROS scavengers. Light-induced intracellular redistribution of TPPS2a was observed, consistent with rupture of endolysosomes where the porphyrin localises. Using the same range of light doses, time-lapse confocal imaging permitted observation of PDT-induced generation of ROS in both 2D and 3D cancer models using fluorescence-based ROS together with specific ROS inhibitors. In addition, the use of red light excitation of the photosensitiser to minimise auto-oxidation of the probes was investigated. In the second part of the study, the photophysical properties of TPPS2a in cells were studied using a time-domain FLIM system with time-correlated single photon counting detection. Owing to the high sensitivity and spatial resolution of this system, we acquired FLIM images that enabled the fluorescence lifetime determination of the porphyrin within the endolysosomal vesicles. Changes in the lifetime dynamics upon prolonged illumination were revealed as the vesicles degraded within the cells.

Impact of changes in collagen construction and molecular state on integrin – binding properties

The interaction between the integrin and collagen is important in cell adhesion and signaling. Collagen, as the main component of extracellular matrix, is a base material for tissue engineering constructs. In tissue engineering, the collagen structure and molecule state may be altered to varying degrees in the process of processing and utilizing, thereby affecting its biological properties. In this work, the impact of changes in collagen structure and molecular state on the binding properties of collagen to integrin α2β1 and integrin specific cell adhesion were explored. The results showed that the molecular structure of collagen is destroyed under the influence of heating, freeze-grinding and irradiation, the triple helix integrity is reduced and molecular breaking degree is increased. The binding ability of collagen to integrin α2β1 is increased with the increase of triple helix integrity and decays exponentially with the increase of molecular breaking degree. The collagen molecular state can also influences the binding ability of collagen to cellular receptor. The collagen fibrils binding to integrin α2β1 and HT1080 cells is stronger than to collagen monomolecule. Meanwhile, the hybrid fibril exhibits a different cellular receptor binding performance from corresponding single species collagen fibril. These findings provide ideas for the design and development of new collagen-based biomaterials and tissue engineering research.

O146: Investigating the cell-matrix interplay in fibrotic remodelling using renal 3D in vitro models

Abstract Introduction The dynamic biophysical microenvironment of the renal extracellular matrix is integral in regulating tissue homeostasis. Matrix remodelling is an iterative process, which guides cell behaviour and pathological fibrosis occurs due to aberrant tissue repair. Fibrosis, characterised by the desmoplastic ECM deposition and tissue stiffening, is prominent in CKD and renal carcinomas. We engineered biomimetic 3D constructs to recapitulate cell-matrix interactions in fibrotic disease progression. Methods Soft collagen-I and laminin constructs (0.2%w/v) were engineered with renal cancer cells (786-O or ACHN) or renal fibroblasts (TK188). Plastic compression was used to generate dense collagen constructs, at 6%w/v collagen density. Mechanical properties were analysed using shear rheology. Gene expression of markers defining the healthy/diseased kidney matrix was determined using qPCR. Results Over 21 days, 786-O cancer cells softened the collagen matrix. Matrix degradation was supported by collagen-I downregulation and MMP7 and vimentin upregulation. Whereas metastatic cancer cells (ACHN) stiffened the dense matrix to ∼1.25kPa, with significant gene upregulation of collagen-I, collagen-IV and LOX. Fibrotic fibroblasts soften the dense matrix by ∼1kPa, with α-SMA and MMP9 upregulation. However, matrix stiffness significantly increases with cancer cell co-cultures. Discussion Renal cancer cells remodel their biophysical environment, altering the construct’s material properties. In our models, collagen density and stromal complexity influences cell behaviour, causing alterations in biomechanics and gene expression. These models can generate physiologically relevant stiffness, enabling investigation between key cell types and the physical environment. Drugs targeting MMPs and LOX will be used to determine if we can disrupt the fibrotic remodelling.

Toward the Development of a Tissue Engineered Gradient Utilizing CRISPR-Guided Gene Modulation.

Cellular, compositional, and mechanical gradients are found throughout biological tissues, especially in transition zones between tissue types. Yet, strategies to engineer such gradients have proven difficult due to the complex nature of these tissues. Current strategies for tissue engineering complex gradients often utilize stem cells; however, these multipotent cells require direction from environmental cues, which can be difficult to control both in vitro and in vivo. In this study, we utilize clustered regularly-interspaced short palindromic repeats (CRISPR)-guided gene modulation to direct the differentiation of multipotent adipose-derived stem cells (ASCs) to demonstrate the effectiveness of CRISPR-engineered cells in tissue engineering applications. Specifically, we screen CRISPR-interference (CRISPRi) constructs targeting the promotors of selected osteogenic inhibitors and demonstrate that ASC osteogenic differentiation and mineral deposition can be regulated with CRISPRi targeting of Noggin without the use of exogenous growth factors in tissue engineered constructs. As a proof of concept, we combine three technologies developed out of our laboratories to demonstrate the controlled deposition of these engineered cells in a gradient with CRISPR-activation multiplex-engineered aggrecan/collagen type-II-chondrogenic ASCs on a high density anisotropic type I collagen construct to create a cell and tissue gradient similar to the fibrocartilage-to-mineralized-fibrocartilage gradient in the enthesis. Our results display the promise of CRISPR-engineered ASCs to produce tissue gradients, similar to what is observed in native tissue.

Aligned Bioelectronic Polypyrrole/Collagen Constructs for Peripheral Nerve Interfacing.

Electrical stimulation has shown promise in clinical studies to treat nerve injuries. This work is aimed to create an aligned bioelectronic construct that can be used to bridge a nerve gap, directly interfacing with the damaged nerve tissue to provide growth support. The conductive three-dimensional bioelectronic scaffolds described herein are composite materials, comprised of conductive polypyrrole (PPy) nanoparticles embedded in an aligned collagen hydrogel. The bioelectronic constructs are seeded with dorsal root ganglion derived primary rat neurons and electrically stimulated in vitro. The PPy loaded constructs support a 1.7-fold increase in neurite length in comparison to control collagen constructs. Furthermore, upon electrical stimulation of the PPy-collagen construct, a 1.8-fold increase in neurite length is shown. This work illustrates the potential of bioelectronic constructs in neural tissue engineering and lays the groundwork for the development of novel bioelectronic materials for neural interfacing applications.

A Systems Approach to Study Collagen Type I Self-Assembly: Kinetics and Morphology.

Collagen type I, the main component of the extracellular matrix in vertebrates, is widely used in tissue engineering applications. This is on account that collagen molecules can self-assemble under certain conditions into 3D fibrillar hydrogels. Although there is an extensive body of literature studying collagen self-assembly, there is a lack of systematic understanding on how different experimental factors, such as pH and temperature, and their cumulative effects guide the self-assembly process. In this work, a comprehensive workflow to study the interactive effects of several assembly parameters on the collagen self-assembly process is implemented. This workflow consists of: 1) efficient statistical sampling based on Design of Experiments, 2) high-throughput and automated data collection and 3) automated data analysis. This approach enables to screen several parameters simultaneously and derive a set of mathematical equationsthat link parameters with the kinetics and morphological aspects of collagen self-assembly, and can be used to design collagen constructs with predefinedcharacteristics.

Assessment of mesh shrinkage using fibroblast-populated collagen matrices: a proof of concept for in vitro hernia mesh testing

PurposeThis study uses free-floating contractile fibroblast-populated collagen matrices (FPCMs) to test the shrinkage of different hernia mesh products. We hope to present this model as a proof of concept for the development of in vitro hernia mesh testing—a novel technology with interesting potential.MethodsFPCMs were formed by seeding Human Dermal Fibroblasts into collagen gels. FPCMs were seeded with three different cell densities and cast at a volume of 500 μl into 24-well plates. Five different mesh products were embedded within the collagen constructs. Gels were left to float freely within culture media and contract over 5 days. Photographs were taken daily and the area of the collagen gel and mesh were measured. Media samples were taken at days 2 and 4 for the purposes of measuring MMP-9 release. After 5 days, dehydrated FPCMs were also examined under light and fluorescence microscopy to assess cell morphology.ResultsTwo mesh products—the mosquito net and large pore lightweight mesh were found to shrink notably more than others. This pattern persisted across all three cell densities. There were no appreciable differences observed in MMP-9 release between products.ConclusionsThis study has successfully demonstrated that commercial mesh products can be successfully integrated into free-floating contractile FPCMs. Not only this, but FPCMs are capable of applying a contractile force upon those mesh products—eliciting different levels of contraction between mesh products. Such findings demonstrate this technique as a useful proof of concept for future development of in vitro hernia mesh testing.

Physical Therapy Aspects on Diabetic Female Osteoporosis Complication

Abstract Osteoporosis is a disease that affects over 40 percent of women over the age of 50. The diabetes-osteoporosis relationship is complex and still incompletely elucidated, despite numerous studies conducted in recent decades(1). The influence of diabetes on bone tissue differs, however, between the forms of type 1 and type 2 diabetes. The purpose of this paper is to highlight the main aspects of the physical therapy in the prophylaxis and treatment of diabetic osteoporosis in females, in the context of proper guidance and an appropriate exercise program. After 35 years of age, the bone continuously loses its substance, a normal and natural phenomenon with the aging. However, this loss can become a serious problem if the initial "bone reserve" was too low or if the bone loss is done too quickly, and especially after the menopause. The result is an increased risk of fracture, either by a normal fall, like in the wrist or hip, or by a moderate lifting effort, as in the case of the vertebrae. Insufficient physical activity, sedentarism, obesity or low body weight, metabolic disorders with absorption deficits lead to demineralization and bone marrow scarring. So, an appropriate exercise program under the auspices of: resistance, posture, balance, are targets that can activate osteoblast in the process of deposition and collagen construction in the bone matrix. A good exercise program in the prophylaxis and treatment of osteoporosis consists of exercise, posture and balance exercises designed for both upper and lower limbs, but also for abdominal and pelvic belts.

Assembly of Rolled-Up Collagen Constructs on Porous Alumina Textiles.

Developing new techniques to prepare free-standing tubular scaffolds has always been a challenge in the field of regenerative medicine. Here, we report a new and simple way to prepare free-standing collagen constructs with rolled-up architecture by self-assembling nanofibers on porous alumina (Al2O3) textiles modified with different silanes, carbon or gold. Following self-assembly and cross-linking with glutaraldehyde, collagen nanofibers spontaneously rolled up on the modified Al2O3 textiles and detached. The resulting collagen constructs had an inner diameter of approximately 2 to 4 mm in a rolled-up state and could be easily detached from the underlying textiles. Mechanical testing of wet collagen scaffolds following detachment yielded mean values of 3.5 ± 1.9 MPa for the tensile strength, 41.0 ± 20.8 MPa for the Young's modulus and 8.1 ± 3.7% for the elongation at break. No roll-up was observed on Al2O3 textiles without any modification, where collagen did not assemble into fibers, either. Blends of collagen and chitosan were also found to roll into fibrous constructs on silanized Al2O3 textiles, while fibrinogen nanofibers or blends of collagen and elastin did not yield such structures. Based on these differences, we hypothesize that textile surface charge and protein charge, in combination with the porous architecture of protein nanofibers and differences in mechanical strain, are key factors in inducing a scaffold roll-up. Further studies are required to develop the observed roll-up effect into a reproducible biofabrication process that can enable the controlled production of free-standing collagen-based tubes for soft tissue engineering.

SP05. A Novel, Patient-specific, Organotypic 3D Platform for Modeling Cell Behavior in the Setting of Malignancy

PURPOSE: With the advent of personalized cancer treatments, patient-specific in vitro models of the breast malignancies are critical for modeling the complex in vivo milieu and to better assess therapeutic efficacy. A primary challenge to developing such platforms is isolating and successfully co-culturing the many primary cell types that constitute the tumor microenvironment. In addition, optimizing for cost-effectiveness of such platforms is critical to making the technology translational. Using patient-derived cells and machine learning-based image analysis, we have developed a low-cost 3D biomimetic platform that allows for the study of cell behavior in a highly organotypic model of breast malignancy. METHODS: Stromal vascular fraction, organoids and mature adipocytes were isolated from breast tissue obtained from healthy female patients undergoing reduction mammoplasty. Isolated cells were embedded in non-ribosylated collagen, creating a biomimetic milieu that approximates the patient-specific in vivo cellular environment (“biomimetic collagen”). 3D collagen constructs consisting of a bottom layer of plain collagen or collagen embedded with RFP-tagged MDA-231 tumor cells followed by a layer of plain or biomimetic collagen were built in a 96-well plate. GFP-tagged human umbilical vascular endothelial (HUVEC) cells were plated in a monolayer layer on top of the collagen to mimic the endothelial barrier. Constructs were imaged with confocal microscopy on days 0 and 7 to assess for endothelial cell organization and migration. Image analysis was completed in Imaris. ANOVA tests for statistical significance were completed in R Studio. RESULTS: Confocal microscopy at day 0 revealed ~800μm thick constructs with distinct tumor and non-tumor collagen layers and a robust HUVEC top monolayer. Confocal images at day 7 were notable organization of the HUVEC layer into 2D tubular networks with some HUVEC below the top monolater indicating migration through the collagen matrix. Our machine-learning based approach was able to reliably and reproducibly parse HUVEC cells from the surrounding cells and collagen, allowing for quantification of cell migration in the Z-axis. Statistical analysis revealed a significant difference in migration across treatment groups (p < 0.01), with endothelial cells in the tumor and biomimetic collagen platform migrating 20-40 microns further than endothelial cells in the other construct designs, a finding retained on intergroup pairwise comparison (p < 0.01). CONCLUSION: This biomimetic platform design and image analysis allows for reliable, reproducible study of discrete endothelial cell interactions with the tumor microenvironment. The finding of enhanced HUVEC migration in the platform with both tumor and biomimetic cells is consistent with the hypothesis that stromal cells, adipocytes and malignant cells enhance the angiogenic capacity of endothelial cells. Importantly, this utilization of patient-derived stromal vascular fraction and mature adipocytes in this platform makes it inherently personalized, a vital component of any future clinically-relevant in vitro cancer platform.

Optimising aerosol jet printing of collagen inks for enhanced piezoelectricity and controlled surface potential

Collagen is a highly versatile protein used in tissue engineering constructs and as a model piezoelectric biomaterial. The piezoelectricity of collagen can be enhanced through the alignment of collagen domains and fibres, although most fabrication techniques used to form dense collagenous constructs do not allow for significant collagen alignment. The use of aerosol jet printing (AJP) mitigates the limitations of using soluble collagen inks for bioprinting or extrusion-based 3D printing, particularly if microfibrillar collagen suspensions are used as a cost-effective and scalable ink source. In this work, Type I and Type II microfibrillar collagen from different anatomical sources were successfully deposited using AJP with two different atomisation methods, namely pneumatic-AJP (p-AJP) and ultrasonic-AJP (u-AJP). The printing parameters were optimised for their piezoelectric amplitude and surface potential. Fourier transform infrared spectra of the films revealed that ultrasonic atomisation did not cause notable denaturation of collagen, although the process resulted in the fractionation and preferential deposition of the oligomeric and gelatinous components within the slurry. The printed collagen samples displayed a piezoelectric response that was four times higher than the values obtained from drop-cast collagen films, and their surface potential was found to be positively correlated to the roughness of the films which can be controlled through the mode of atomisation. These results indicate the ability to enhance and control the piezoelectricity and surface potential using p-AJP and u-AJP, which offers a promising physical modulation technique to tailor cell adhesion, proliferation or differentiation for collagen-based tissue engineering constructs.

Evaluation of a Novel Graft-Holding Solution in Hair Transplantation: A Randomized Controlled Clinical Study.

Hair transplantation has become a popular choice for alopecia treatment; however, postsurgical hair shedding still annoys both patients and surgeons. To explore the impact of graft-holding solution on postsurgical hair shedding and testify the protective efficacy of histidine-tryptophan-ketoglutarate solution with adenosine triphosphate and deferoxamine (HTK-AD). There were 240 patients enrolled in the study, and the follicles were placed into either HTK-AD or Ringer solution (RS). Masson staining and live/dead staining were performed to evaluate graft morphology and apoptosis levels, respectively. The between-group comparison of postsurgical graft shedding, survival rate, complications, and patient satisfaction was performed. Grafts in HTK-AD maintained organized dense collagen construction and higher cell viability, but those preserved in RS became soft, which hindered implantation. Histidine-tryptophan-ketoglutarate solution with adenosine triphosphate and deferoxamine significantly reduced the incidence of postsurgical hair shedding (73.81% vs 95%), delayed shedding onset, and diminished shedding amount versus RS (p < .05) when ≥3,000 grafts were transplanted. The shedding duration was shortened, and hair regrowth started earlier in HTK-AD versus RS (p < .05); thus, satisfaction was increased. The final survival rate showed no difference between 2 groups. Histidine-tryptophan-ketoglutarate solution with adenosine triphosphate and deferoxamine is superior to RS for hair graft preservation because it improves graft viability and alleviates postsurgical shedding.

Differential contractility regulates cancer stem cell migration

Cancer stem cells (CSCs) are known to have a high capacity for tumor initiation and the formation of metastases. We have previously shown that in collagen constructs mimetic of aligned extracellular matrix architectures observed in carcinomas, breast CSCs demonstrate enhanced directional and total motility compared with more differentiated carcinoma populations. Here, we show that CSCs maintain increased motility in diverse environments including on 2D elastic polyacrylamide gels of various stiffness, 3D randomly oriented collagen matrices, and ectopic cerebral slices representative of a common metastatic site. A consistent twofold increase of CSC motility across platforms suggests a general shift in cell migration mechanics between well-differentiated carcinoma cells and their stem-like counterparts. To further elucidate the source of differences in migration, we demonstrate that CSCs are less contractile than the whole population (WP) and develop fewer and smaller focal adhesions and show that enhanced CSC migration can be tuned via contractile forces. The WP can be shifted to a CSC-like migratory phenotype using partial myosin II inhibition. Inversely, CSCs can be shifted to a less migratory WP-like phenotype using microtubule-destabilizing drugs that increase contractility or by directly enhancing contractile forces. This work begins to reveal the mechanistic differences driving CSC migration and raises important implications regarding the potentially disparate effects of microtubule-targeting agents on the motility of different cell populations.

Adipose-Derived Stem Cells in Reinforced Collagen Gel: A Comparison between Two Approaches to Differentiation towards Smooth Muscle Cells.

Scaffolds made of degradable polymers, such as collagen, polyesters or polysaccharides, are promising matrices for fabrication of bioartificial vascular grafts or patches. In this study, collagen isolated from porcine skin was processed into a gel, reinforced with collagen particles and with incorporated adipose tissue-derived stem cells (ASCs). The cell-material constructs were then incubated in a DMEM medium with 2% of FS (DMEM_part), with added polyvinylalcohol nanofibers (PVA_part sample), and for ASCs differentiation towards smooth muscle cells (SMCs), the medium was supplemented either with human platelet lysate released from PVA nanofibers (PVA_PL_part) or with TGF-β1 + BMP-4 (TGF + BMP_part). The constructs were further endothelialised with human umbilical vein endothelial cells (ECs). The immunofluorescence staining of alpha-actin and calponin, and von Willebrand factor, was performed. The proteins involved in cell differentiation, the extracellular matrix (ECM) proteins, and ECM remodelling proteins were evaluated by mass spectrometry on day 12 of culture. Mechanical properties of the gels with ASCs were measured via an unconfined compression test on day 5. Gels evinced limited planar shrinkage, but it was higher in endothelialised TGF + BMP_part gel. Both PVA_PL_part samples and TGF + BMP_part samples supported ASC growth and differentiation towards SMCs, but only PVA_PL_part supported homogeneous endothelialisation. Young modulus of elasticity increased in all samples compared to day 0, and PVA_PL_part gel evinced a slightly higher ratio of elastic energy. The results suggest that PVA_PL_part collagen construct has the highest potential to remodel into a functional vascular wall.

Hyaluronic acid hydrogels support to generate integrated bone formation through endochondral ossification in vivo using mesenchymal stem cells.

Engineered cartilage tissue from differentiated mesenchymal stem cells (MSCs) can generate bone in vivo through endochondral ossification (ECO). This ECO-mediated approach has the potential to circumvent the severe problems associated with conventional MSC-based bone tissue engineering techniques that lack mechanisms to induce angiogenesis. Hyaluronic acid (HA) is a key component in the cartilage extracellular matrix. However, the ECO-supporting properties of HA remain largely unclear. This study aimed to compare the ability of HA and collagen hydrogels to support in vitro differentiation of MSC-based hypertrophic cartilage tissues and to promote endochondral bone formation in vivo. Following the chondrogenic and hypertrophic differentiation in vitro, both HA and collagen constructs accumulated sulfated glycosaminoglycan (sGAG) and type 1, type II, and type X collagen. However, HA hydrogels exhibited a more uniform distribution of sGAG, type 1 collagen, type X collagen, and osteocalcin proteins; in addition, the cells embedded in the hydrogels had more rounded cell morphologies than those in the collagen constructs. At week 5 of in vitro culture, two to three constructs were implanted into a subcutaneous pocket in nude mice and harvested after 4 and 8 weeks. Both HA and collagen constructs promoted endochondral bone formation with vascularization and bone marrow development; however, the HA constructs fused to form integrated bone tissues and the bone marrow developed along the space between the two adhered grafts in all implanted pockets (n = 5). In the collagen constructs, the integration was observed in 40% of the pockets (n = 5). Microcomputer CT analysis revealed that the bone volume of HA constructs was larger than that of collagen constructs. In conclusion, compared to collagen hydrogels, HA hydrogels had superior potential to generate integrated bone with vascularization and bone marrow development. This study provides valuable insights for applying ECO-mediated bone tissue engineering approaches for the repair of critical-sized bone defects.

Iron Deficiency may be a Risk Factor for Inguinal Hernia Development in Children.

This case control study aimed to investigate whether the routine hemogram and biochemical parameters of pediatric patients who have undergone surgery for inguinal hernia are associated with the etiopathogenesis of the disease. Eighty cases of inguinal hernia surgery performed between January 2019 and November 2022 were included in the study. A control group was also established using hospital records, consisting of eighty pediatric patients without any known history of hematological or metabolic disease or use of regular medication. Statistical analysis was conducted to compare the total hemoglobin (Hgb), hematocrit (Htc), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), erythrocyte distribution width (RDW) and thrombocyte (PLT) values in both groups. The age range of the pediatric patients was 1-14 years. Of the eighty children, 47 (58.8%) were male and 33 (41.3%) were female, with a mean age of 5.79±3.26. The values of Hgb, Htc, MCH, MCHC, and MCV in the inguinal hernia patients were found to be statistically significantly lower than those in the control group (p<0.05). Additionally, the patient RDW values were found to be statistically significantly higher than those in the control group (p<0.05). Compared to the control group, the observed decrease in MCH, MCHC, MCV, Hgb, HTC values, as well as the increase in RDW in patient group, suggests a predisposing effect of iron deficiency. These specific changes suggested that iron deficiency may lead structural changes in the collagen construction and may contribute the etiopathogenesis of childhood inguinal hernia.

Fibrin sealant as a delivery vehicle for cells, antibiotics, growth factors, and painkillers

Fibrin sealant has vast uses in surgical settings for both cellular and noncellular delivery. Some advantages include biocompatibility, ability to support cell attachment, and controlled degradation rate. There are many clinical applications, from wound healing to improving bone defects to being used as an adjunct to surgery. It can also serve as a suitable delivery vehicle for cells, steroids, antibiotics, growth factors, chemotherapeutic agents, and painkillers. The composition of fibrin sealant can be altered to allow for controlled release, making it an attractive delivery system. Lastly, a wound healing model with 2 defects in the collagen construct may serve as a future application that utilizes fibrin sealant as a delivery system. This review highlights different uses of fibrin sealant as a delivery vehicle for cells, steroids, antibiotics, chemotherapeutic agents, growth factors, and painkillers

Xeno-free self-assembling peptide scaffolds for building 3D organotypic skin cultures.

Organotypic skin cultures represent in vitro models of skin which can be used for disease modeling, tissue engineering, and screening applications. Non‐human collagen is currently the gold standard material used for the construction of the supporting matrix, however, its clinical applications are limited due to its xenogeneic origin. We have developed a novel peptide hydrogel‐based skin construct that shows a pluristratified epidermis, basement membrane, and dermal compartment after 3 weeks of in vitro culture. Peptide‐based constructs were compared to collagen‐based constructs and stratification marker expression was histologically higher in peptide constructs than in collagen constructs. Transepithelial electrical resistance also showed mature barrier function in peptide constructs. This study presents a novel application of the self‐assembling peptide hydrogel in a defined xeno‐free in vitro system.