Advances in In Vitro Blood-Air Barrier Models and the Use of Nanoparticles in COVID-19 Research.

Respiratory infections caused by coronaviruses (CoVs) have become a major public health concern in the past two decades as revealed by the emergence of SARS-CoV in 2002, MERS-CoV in 2012, and SARS-CoV-2 in 2019. The most severe clinical phenotypes commonly arise from exacerbation of immune response following the infection of alveolar epithelial cells localized at the pulmonary blood-air barrier. Preclinical rodent models do not adequately represent the essential genetic properties of the barrier, thus necessitating the use of humanized transgenic models. However, existing monolayer cell culture models have so far been unable to mimic the complex lung microenvironment. In this respect, air-liquid interface models, tissue engineered models, and organ-on-a-chip systems, which aim to better imitate the infection site microenvironment and microphysiology, are being developed to replace the commonly used monolayer cell culture models, and their use is becoming more widespread every day. On the contrary, studies on the development of nanoparticles (NPs) that mimic respiratory viruses, and those NPs used in therapy are progressing rapidly. The first part of this review describes in vitro models that mimic the blood-air barrier, the tissue interface that plays a central role in COVID-19 progression. In the second part of the review, NPs mimicking the virus and/or designed to carry therapeutic agents are explained and exemplified.

Composite sponges from sheep decellularized small intestinal submucosa for treatment of diabetic wounds.

Despite the fast development of technology in the world, diabetic foot wounds cause deaths and massive economical losses. Diabetes comes first among the reasons of non traumatic foot amputations. To reduce the healing time of these fast progressing wounds, effective wound dressings are in high demand. In our study, sheep small intestinal submucosa (SIS) based biocompatible sponges were prepared after SIS decellularization and their wound healing potential was investigated on full thickness skin defects in a diabetic rat model. The decellularized SIS membranes had no cytotoxic effects on human fibroblasts and supported capillary formation by HUVECs in a fibroblast-HUVEC co-culture. Glutaraldehyde crosslinked sponges of three different compositions were prepared to test in a diabetic rat model: gelatin (GS), gelatin: hyaluronic acid (GS:HA) and gelatin: hyaluronic acid: SIS (GS:HA:SIS). The GS:HA:SIS sponges underwent a 24.8 ± 5.4% weight loss in a 7-day in vitro erosion test. All sponges had a similar Young's modulus under compression but GS:HA:SIS had the highest (5.00 ± 0.04 kPa). Statistical analyses of histopathological results of a 12-day in vivo experiment revealed no significant difference among the control, GS, GS:HA, and GS:HA:SIS transplanted groups in terms of granulation tissue thickness, collagen deposition, capillary vessel formation, and foreign body reaction (P > 0.05). On the other hand, in the GS:HA:SIS transplanted group 80% of the animals had a complete epidermal regeneration and this was significantly different than the control group (30%, P < 0.05). Preclinical studies revealed that the ECM of sheep small intestinal submucosa can be used as an effective biomaterial in diabetic wound healing.

An in vitro 3D diabetic human skin model from diabetic primary cells.

Diabetes mellitus, a complex metabolic disorder, leads to many health complications like kidney failure, diabetic heart disease, stroke, and foot ulcers. Treatment approaches of diabetes and identification of the mechanisms underlying diabetic complications of the skin have gained importance due to continued rapid increase in the diabetes incidence. A thick and pre-vascularized in vitro 3D type 2 diabetic human skin model (DHSM) was developed in this study. The methacrylated gelatin (GelMA) hydrogel was produced by photocrosslinking and its pore size (54.85 ± 8.58 µm), compressive modulus (4.53 ± 0.67 kPa) and swelling ratio (17.5 ± 2.2%) were found to be suitable for skin tissue engineering. 8% GelMA hydrogel effectively supported the viability, spreading and proliferation of human dermal fibroblasts. By isolating dermal fibroblasts, human umbilical vein endothelial cells and keratinocytes from type 2 diabetic patients, an in vitro 3D type 2 DHSM, 12 mm in width and 1.86 mm thick, was constructed. The skin model consisted of a continuous basal epidermal layer and a dermal layer with blood capillary-like structures, ideal for evaluating the effects of anti-diabetic drugs and wound healing materials and factors. The functionality of the DHSM was showed by applying a therapeutic hydrogel into its central wound; especially fibroblast migration to the wound site was evident in 9 d. We have demonstrated that DHSM is a biologically relevant model with sensitivity and predictability in evaluating the diabetic wound healing potential of a therapeutic material.

Mapping the Molecular Basis and Markers of Papillary Thyroid Carcinoma Progression and Metastasis Using Global Transcriptome and microRNA Profiling.

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer (TC). In a subgroup of patients with PTC, the disease progresses to an invasive stage or in some cases to distant organ metastasis. At present, there is an unmet clinical and diagnostic need for early identification of patients with PTC who are at risk of disease progression or metastasis. In this study, we report several molecular leads and potential biomarker candidates of PTC metastasis for further translational research. The study design was based on comparisons of PTC in three different groups using cross-sectional sampling: Group 1, PTC localized to the thyroid (n = 20); Group 2, PTC with extrathyroidal progression (n = 22); and Group 3, PTC with distant organ metastasis (n = 20). Global transcriptome and microRNAs (miRNA) analyses were conducted using an initial screening set comprising nine formalin-fixed paraffin-embedded PTC samples obtained from three independent patients per study group. The findings were subsequently validated by quantitative real-time polymerase chain reaction (qRT-PCR) using the abovementioned independent patient sample set (n = 62). Comparative analyses of differentially expressed miRNAs showed that miR-193-3p, miR-182-5p, and miR-3607-3p were novel miRNAs associated with PTC metastasis. These potential miRNA biomarkers were associated with TC metastasis and miRNA-target gene associations, which may provide important clinicopathological information on metastasis. Our findings provide new molecular leads for further translational biomarker research, which could facilitate the identification of patients at risk of PTC disease progression or metastasis.

In vitro antibacterial activity of ciprofloxacin loaded chitosan microparticles and their effects on human lung epithelial cells.

Chitosan (CS), due to its inherent mucoadhesive property and biofilm penetration ability, can be considered as very potent vehicle for local drug delivery to the lungs. This study reports on the preparation and in vitro antibacterial activity and cytotoxicity determination of ciprofloxacin loaded chitosan (Cipro-CS) microparticles with size in the range of 0.1-1 µm, which may provide advantages of lower nanotoxicity and lower local clearance. Cipro-CS microparticles were prepared by ionic gelation method and their size, zeta potential and drug release pattern determined. The antibacterial activities of CS and Cipro-CS microparticles against pneumonia causing agents, namely Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, were evaluated by determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The biocompatibility of the microparticles was tested in the human lung epithelial cell (BEAS-2B) culture, and microparticle association with the bacteria and epithelial cells was evaluated by transmission electron microscopy. Only the Cipro-CS microparticles, but not the CS microparticles, inhibited bacterial growth at concentrations not significantly cytotoxic to BEAS-2B cells. The Cipro-CS microparticles were able to damage the cell wall and membrane of the bacteria, and the ones ≤200 nm in size were internalized by both the BEAS-2B cells and the microorganisms.

Microfibrous scaffolds from poly(l-lactide-co-ε-caprolactone) blended with xeno-free collagen/hyaluronic acid for improvement of vascularization in tissue engineering applications.

Success of 3D tissue substitutes in clinical applications depends on the presence of vascular networks in their structure. Accordingly, research in tissue engineering is focused on the stimulation of angiogenesis or generation of a vascular network in the scaffolds prior to implantation. A novel, xeno-free, collagen/hyaluronic acid-based poly(l-lactide-co-ε-caprolactone) (PLC/COL/HA) (20/9.5/0.5 w/w/w) microfibrous scaffold was produced by electrospinning. Collagen types I and III, and hyaluronic acid were isolated from human umbilical cords and blended with the GMP grade PLC. When compared with PLC scaffolds the PLC/COL/HA had higher water uptake capacity (103% vs 66%) which may have contributed to the decrease in its Young's Modulus (from 1.31 to 0.89 MPa). The PLC/COL/HA better supported adipose tissue-derived mesenchymal stem cell (AT MSC) adhesion; within 24 h the cell number on the PLC/COL/HA scaffolds was 3 fold higher. Co-culture of human umbilical vein endothelial cells and AT MSCs induced capillary formation on both scaffold types, but the PLC/COL/HA led to formation of interconnected vessels whose total length was 1.6 fold of the total vessel length on PLC. Clinical use of this scaffold would eliminate the immune response triggered by xenogeneic collagen and transmission of animal-borne diseases while promoting a better vascular network formation.

Skeletal muscle patch engineering on synthetic and acellular human skeletal muscle originated scaffolds.

The reconstruction of skeletal muscle tissue is currently performed by transplanting a muscle tissue graft from local or distant sites of the patient's body, but this practice leads to donor site morbidity in case of large defects. With the aim of providing an alternative treatment approach, skeletal muscle tissue formation potential of human myoblasts and human menstrual blood derived mesenchymal stem cells (hMB-MSCs) on synthetic [poly(l-lactide-co-caprolactone), 70:30] scaffolds with oriented microfibers, human muscle extracellular matrix (ECM), and their hybrids was investigated in this study. The reactive muscle ECM pieces were chemically crosslinked to the synthetic scaffolds to produce the hybrids. Cell proliferation assay WST-1, scanning electron microscopy (SEM), and immunostaining were carried out after culturing the cells on the scaffolds. The ECM and the synthetic scaffolds were effective in promoting spontaneous myotube formation from human myoblasts. Anisotropic muscle patch formation was more successful when human myoblasts were grown on the synthetic scaffolds. Nonetheless, spontaneous differentiation could not be induced in hMB-MSCs on any type of the scaffolds. Human myoblast-synthetic scaffold combination is promising as a skeletal muscle patch, and can be improved further to serve as a fast integrating functional patch by introducing vascular and neuronal networks to the structure. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 879-890, 2017.

Collagen scaffolds with in situ-grown calcium phosphate for osteogenic differentiation of Wharton's jelly and menstrual blood stem cells.

The aim of this research was to investigate the osteogenic differentiation potential of non-invasively obtained human stem cells on collagen nanocomposite scaffolds with in situ-grown calcium phosphate crystals. The foams had 70% porosity and pore sizes varying in the range 50-200 µm. The elastic modulus and compressive strength of the calcium phosphate containing collagen scaffolds were determined to be 234.5 kPa and 127.1 kPa, respectively, prior to in vitro studies. Mesenchymal stem cells (MSCs) obtained from Wharton's jelly and menstrual blood were seeded on the collagen scaffolds and proliferation and osteogenic differentiation capacities of these cells from two different sources were compared. The cells on the composite scaffold showed the highest alkaline phosphatase activity compared to the controls, cells on tissue culture polystyrene and cells on collagen scaffolds without in situ-formed calcium phosphate. MSCs isolated from both Wharton's jelly and menstrual blood showed a significant level of osteogenic activity, but those from Wharton's jelly performed better. In this study it was shown that collagen nanocomposite scaffolds seeded with cells obtained non-invasively from human tissues could represent a potential construct to be used in bone tissue engineering.

Production of a composite hyaluronic acid/gelatin blood plasma gel for hydrogel-based adipose tissue engineering applications.

Standard approaches to soft-tissue reconstruction include autologous adipose tissue transplantation, but most of the transferred adipose tissue is generally reabsorbed in a short time. To overcome this problem, long lasting implantable hydrogel materials that can support tissue regeneration must be produced. The purpose of this study was to evaluate the suitability of composite 3D natural origin scaffolds for reconstructive surgery applications through in vitro tests. The Young's modulus of the glutaraldehyde crosslinked hyaluronic acid/gelatin (HA/G) plasma gels, composed of human platelet-poor plasma, gelatin and human umbilical cord hyaluronic acid, was determined as 3.5 kPa, close to that of soft tissues. The composite HA/G plasma gels had higher porosity than plain plasma gels (72.5% vs. 63.86%). Human adipose tissue derived stem cells (AD-MSCs) were isolated from human lipoaspirates and characterized with flow cytometry, and osteogenic and adipogenic differentiation. Cell proliferation assay of AD-MSCs on the HA/G plasma gels revealed the nontoxic nature of these constructs. Adipogenic differentiation was distinctly better on HA/G plasma gels than on plain plasma gels. The results showed that the HA/G plasma gel with its suitable pore size, mechanical properties and excellent cell growth and adipogenesis supporting properties can serve as a useful scaffold for adipose tissue engineering applications.

The short- and long- term effects of estrogen deficiency on apoptosis in musculoskeletal tissues: an experimental animal model study.

BACKGROUND: Estrogen is the major sex steroid affecting the growth, remodeling, and homeostasis of the female skeleton. Estrogen loss in postmenopausal women leads to osteoporosis. The aim of this study was to evaluate the early and long- term effects of estrogen loss on bones, tendons, muscles, and menisci in ovariectomized rats.  METHODS: Fifteen rats were randomized into three groups of five animals each. The first group was the control group with no additional surgical procedure, but the rest (groups 2 and 3) were bilaterally ovariectomized . All animals in the group 2 were sacrificed at 14th week to evaluate the short- term effect, and all of other animals in the groups 1 and 3 were sacrificed at 28th week to analyze the long- term effect of estrogen loss in the ovariectomized group and to control with the group 1. Quadriceps muscles, Achilles tendons, menisci, and femur cortical bones from both lower extremities were taken. The amount of apoptosis was measured. RESULTS: There was a significant increase in cell apoptosis in bones, muscles, and tendons with insignificant increase in cell apoptosis in menisci at early and late periods in rats with ovariectomies than the control.  CONCLUSION: The results indicated that estrogen loss after ovariectomy does not only affect bones; it may also increase cell apoptosis in different tissues such as muscles, tendons, and menisci.

Femtosecond laser treatment of 316L improves its surface nanoroughness and carbon content and promotes osseointegration: An in vitro evaluation.

Cell-material surface interaction plays a critical role in osseointegration of prosthetic implants used in orthopedic surgeries and dentistry. Different technical approaches exist to improve surface properties of such implants either by coating or by modification of their topography. Femtosecond laser treatment was used in this study to generate microspotted lines separated by 75, 125, or 175µm wide nanostructured interlines on stainless steel (316L) plates. The hydrophobicity and carbon content of the metallic surface were improved simultaneously through this method. In vitro testing of the laser treated plates revealed a significant improvement in adhesion of human endothelial cells and human bone marrow mesenchymal stem cells (hBM MSCs), the cells involved in microvessel and bone formation, respectively, and a significant decrease in fibroblast adhesion, which is implicated in osteolysis and aseptic loosening of prostheses. The hBM MSCs showed an increased bone formation rate on the laser treated plates under osteogenic conditions; the highest mineral deposition was obtained on the surface with 125µm interline distance (292±18mg/cm(2) vs. 228±43mg/cm(2) on untreated surface). Further in vivo testing of these laser treated surfaces in the native prosthetic implant niche would give a real insight into their effectiveness in improving osseointegration and their potential use in clinical applications.

Effect of low level laser therapy and zoledronate on the viability and ALP activity of Saos-2 cells.

A limited number of clinical studies indicate the supportive role of low level laser therapy (LLLT) on medical and/or surgical approaches carried out in treatment modalities for bisphosphonate related necrosis of jaws (BRONJ), the most common side effect of bisphosphonates used to inhibit bone resorption. The purpose of this study was to investigate the effects of LLLT on cell proliferation and alkaline phosphatase (ALP) activity of human osteoblast-like cells (Saos-2) treated with different doses of zoledronate, the most potent bisphosphonate. Saos-2 cells were treated with different concentrations of zoledronate and were irradiated with diode laser (wavelength 808 nm, 10 s, 0.25 or 0.50 W). Cell numbers and ALP activity of the cells were determined. LLLT mildly increased the proliferation rate or ALP activity, while zoledronate reduced both. When applied together, LLLT lessened the detrimental effects of zoledronate and improved cell function and/or proliferation. Based on the results of this study, it was concluded that LLLT has biostimulative effects on Saos-2 cells, even after treatment with zoledronate. LLLT may serve as a useful supportive method for BRONJ treatment through enhancement of healing by osteoblasts.

A 3D aligned microfibrous myocardial tissue construct cultured under transient perfusion.

The goal of this study was to design and develop a myocardial patch to use in the repair of myocardial infarctions or to slow down tissue damage and improve long-term heart function. The basic 3D construct design involved two biodegradable macroporous tubes, to allow transport of growth media to the cells within the construct, and cell seeded, aligned fiber mats wrapped around them. The microfibrous mat housed mesenchymal stem cells (MSCs) from human umbilical cord matrix (Wharton's Jelly) aligned in parallel to each other in a similar way to cell organization in native myocardium. Aligned micron-sized fiber mats were obtained by electrospinning a polyester blend (PHBV (5% HV), P(L-D,L)LA (70:30) and poly(glycerol sebacate) (PGS)). The micron-sized electrospun parallel fibers were effective in Wharton's Jelly (WJ) MSCs alignment and the cells were able to retract the mat. The 3D construct was cultured in a microbioreactor by perfusing the growth media transiently through the macroporous tubing for two weeks and examined by fluorescence microscopy for cell distribution and preservation of alignment. The fluorescence images of thin sections of 3D constructs from static and perfused cultures confirmed enhanced cell viability, uniform cell distribution and alignment due to nutrient provision from inside the 3D structure.

A comprehensive characterization study of human bone marrow mscs with an emphasis on molecular and ultrastructural properties.

Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) continue to draw attention of researchers in the fields of basic science and medicine due to their indispensible regenerative, reparative, angiogenic, anti-apoptotic, and immunosuppressive properties, all of which collectively point out their enormous therapeutic potential. There is still, however, a need for further investigation of their characteristics to broaden their field of use and learn much more about how to control their fate and improve their therapeutic effectiveness. hBM-MSCs were extensively characterized in terms of their growth characteristics, genetic stability, and differentiation capability to the mesodermal and ectodermal cell lineages; a special emphasis was given to their phenotypic and ultrastructural properties. Expression of embryonic stem cell markers Oct4, Rex-1, FoxD-3, Sox2, and Nanog was shown with real-time PCR. Transmission electron microscopy revealed the ultrastructural characteristics of hBM-MSCs; they had pale, irregularly shaped and large euchromatic nuclei, and two distinct areas in their cytoplasm: an intensely stained inner zone rich in mitochondria and rough endoplasmic reticulum (rER) with dilated cisternae and a relatively peripheral zone poor in organelles. hBM-MSCs expressed adipogenic (adipophilin and PPARγ), myogenic (desmin, myogenin, α-SMA), neurogenic (γ-enolase, MAP2a,b, c-fos, nestin, NF-H, NF-L, GFAP, ß3-tubulin), osteogenic (osteonectin, osteocalcin, osteopontin, Runx-2, type I collagen), and chondrogenic (type II collagen, SOX9) markers either at RNA or protein level even under basal conditions, without any stimulation towards differentiation. The differentiation potential of hBM-MSCs to adipogenic, osteogenic, and neurogenic lineages was shown by using the relevant differentiation factors.

Tissue engineering of bone on micropatterned biodegradable polyester films.

In this study, the effect of cell alignment on proliferation and phenotype expression of rat bone marrow derived osteoblasts on micropatterned (MP) PHBV and P(L/D,L)LA films with 27 microm wide parallel microgrooves was investigated. Immobilization of fibrinogen (Fb) on film surface by adsorption increased hydrophilicity, while covalent immobilization decreased it. Amount of Fb immobilized was significantly higher upon covalent bonding (153.1+/-42.4 microg Fb/cm2) than when adsorbed (10.0+/-3.3 microg Fb/cm2). It was observed that the presence of MP did not influence cell proliferation in the long run. Osteoblasts on MP films with adsorbed (MP Fb(a)) and covalently immobilized Fb (MP Fb(i)) aligned parallel to the groove axis with mean deviation angles of 10.59+/-23.47 and 29.02+/-33.03 degrees, respectively, while on tissue culture polystyrene (TCP), on unpatterned films (UNP) and on UNP with adsorbed Fb (UNP Fb(a)) alignment with an arbitrary axis was much higher: 46.66+/-24.98, 48.72+/-31.19, 47.74+/-27.29 degrees, respectively. Fb-free MP films were not effective in cell alignment, and clumps were formed. Cell alignment achieved on MP Fb(a) films did not influence cell proliferation, but increased differentiation, as shown by ALP activity per cell and the evenness and the amount of calcium phosphate deposition. It was concluded that orientation of cells was influential on their differentiation and also, MP cell carriers with chemical cues on their surfaces are important in improving tissue repair.

Novel surface patterning approaches for tissue engineering and their effect on cell behavior.

Methods for the creation of specially designed surfaces for use in the preparation of tailor-made tissue constructs with the ultimate aim of tissue engineering are reviewed here. Fundamental aspects of cell adhesion, proliferation and differentiation and the parameters involved in these processes are discussed. A survey of recent micro- and nano-technological methods for creating physical and chemical cues on tissue engineering carriers is presented. This overview is supported with data from the literature on various applications of different cells on materials with widely differing chemistries and physical properties. Interactions between different cell types and micro- and nano-fabricated substrates are summarized.