Tissue Culture Dishes Research Articles

Formation of linear arrays of holes in self-assembled collagen films

Collagen is one of the main constituents of mammalian extracellular matrix and is used extensively as a coating for tissue culture dishes and medical implants to promote cell growth and proliferation. By modulating the topography of the collagen coating at the nanometer to micrometer length scales, it is possible to achieve spatial control over cell growth and morphology. In this work, we are exploring the self-assembly of a thin collagen film on a glass substrate as a way to create new nanoscale surface features. By controlling the collagen concentration and adding an oscillatory flow, we are able to enrich the collagen film surface with a localized pattern of ripples oriented perpendicular to the flow direction. We propose that these ripples are the result of dewetting of the collagen film that leads to the formation of adjacent holes. We observe that individual holes form with an anisotropic rim due to the microstructure of the deposited collagen fibril network. This intrinsic anisotropy and the oscillatory flow yield new holes being formed in the film next to existing rims. As holes keep growing deeper, the rims extend along the flow direction, and the holes appear rectangular in shape, which gives the linear array of holes the apparent morphology of a ripple. Overall, we are able to create localized ripples at the surface of collagen films that would be difficult to produce via standard nanofabrication techniques.

Pulmonary matrix-derived hydrogels from patients with idiopathic pulmonary fibrosis induce a proinflammatory state in lung fibroblasts in vitro.

Idiopathic pulmonary fibrosis (IPF), one of the most common forms of interstitial lung disease, is a poorly understood, chronic, and often fatal fibroproliferative condition with only two FDA-approved medications. Understanding the pathobiology of the fibroblast in IPF is critical to evaluating and discovering novel therapeutics. Using a decellularized lung matrix derived from patients with IPF, we generate three-dimensional hydrogels as in vitro models of lung physiology and characterize the phenotype of fibroblasts seeded into the hydrogels. When cultured in IPF extracellular matrix hydrogels, IPF fibroblasts display differential contractility compared with their normal counterparts, lose the classical myofibroblast marker α-smooth muscle actin, and increase expression of proinflammatory cytokines compared with fibroblasts seeded two-dimensionally on tissue culture dishes. We validate this proinflammatory state in fibroblast-conditioned media studies with monocytes and monocyte-derived macrophages. These findings add to a growing understanding of the lung microenvironment effect on fibroblast phenotypes, shed light on the potential role of fibroblasts as immune signaling hubs during lung fibrosis, and suggest intervention in fibroblast-immune cell cross-talk as a possible novel therapeutic avenue.

Exploiting non-permissive CHO cells as a rapid and efficient method for recombinant HSV-1 isolation

Using herpes simplex virus type 1 (HSV-1) as a therapeutic tool has recently emerged as a promising strategy for enhancing the treatment of various cancers, particularly those associated with the nervous system, which is the virus's natural site of infection. These viruses are specifically engineered to infect and eradicate tumor cells while leaving healthy cells unharmed. To introduce targeted mutations in specific viral genes, gene-modification techniques such as shuttle vector homologous recombination are commonly employed. Plaque purification is then utilized to select and purify the recombinant virus from the parental viruses. However, plaque purification becomes problematic when the insertion of the desired gene at the target site hampers progeny virus replication, resulting in a lower titer of cell-released virus than the parental virus. This necessitates a laborious initial screening process using approximately 10–15 tissue culture dishes (10 cm), making plaque purification time-consuming and demanding. Although the recently developed CRISPR-Cas9 system significantly enhances the efficiency of homologous integration and editing precision in viral genes, the purification of recombinant variants remains a tedious task. In this study, we propose a rapid and innovative method that employs non-permissive Chinese hamster ovary (CHO) cells, representing a remarkable improvement over the aforementioned arduous process. With this approach, only 1–2 rounds of plaque purification are required. Our proposed protocol demonstrates great potential as a viable alternative to current methods for isolating and purifying recombinant HSV-1 variants expressing fluorescent reporter genes using CHO cells and plaque assays.

Effects of p300 inhibition on prostate cancer cell growth

Background: Radiation is a central component of many anti-cancer therapy regimens, utilized for more than half of all cancer patients. Despite advances in the delivery and success of radiation treatment, many individuals express, or will develop, radioresistance, a major contributor to treatment failure and malignant progression. While the etiology of radioresistance is complex, it may be mediated in part by expression of p300, a histone acetyltransferase known to facilitate DNA repair. We hypothesized that inhibition of p300 would increase radiosensitivity of prostate cancer cells in vitro. Methods: Human prostate adenocarcinoma (PC-3) cells were grown in tissue culture flasks incubated at 37° C with 5% CO2. Cells were randomized to receive 1 μM CCS 1477, a selective inhibitor of p300, or vehicle for 1 hour prior to a single treatment of 0 Gy (NR+ or NR-, respectively) or 2 Gy radiation (R+ or R-, respectively). Four hours after radiation, cells were seeded into 100 mm diameter tissue culture dishes and incubated for 10 days. Cells were then stained, and colonies > 50 cells were counted to determine clonogenic survival. Cell survival was corrected for plating effciency and group comparisons were made using a two-way ANOVA. Results: Results were determined from the average of 3 separate experiments. Compared to non-radiated controls (NR-), survival of R- was reduced to 47%, while survival of R+ was reduced to 32%. However, there was no significant difference between % survival of R- and R+. Conclusions: In vitro, 1 μM exposure to CCS 1477 does not reduce clonogenic survival in PC-3 cells subjected to 2 Gy radiation. The duration of exposure and concentration of CCS 1477 may not be adequate to elicit significant improvements in radiosensitivity of PC-3 cells to 2 Gy radiation. Future experiments will explore the effects of varying durations of exposure and concentrations of CCS 1477. Additionally, it remains to be determined whether CCS 1477 improves radiosensitivity in other cancer cell lines (e.g., breast cancer). Johnson Cancer Research Center. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Quandary of Cellular Fractionation — Optimizing Ambion™ Paris System to Advance HPV16 Cancer Research

Background and Hypothesis: Human Papillomavirus (HPV) is the causative agent in nearly all cervical cancer cases. It has been shown that the HPV type 16 E6 protein interacts directly with the host protein NFX1-123. Short-term studies have shown that NFX1-123 remains in the cytoplasm; however, it has not been investigated whether NFX1-123 actually translocates to the nucleus in the long term. We hypothesize that over time, NFX1-123 translocates to the nucleus of the cell in long term cultures with 16E6. This present study seeks to optimize the AmbionTM Paris system to allow for pure, proper separation of the cytoplasmic and nuclear cellular compartments.
 Project Methods: Three biologically unique backgrounds of human foreskin keratinocytes (HFKs) were cultured in a monolayer tissue culture dish. Using the AmbionTM Paris system, proteins were isolated as whole cell extracts, or nuclear and cytoplasmic fractions. For one lysis method, only protease inhibitors were added to the lysis buffers of the AmbionTM Paris system. For another lysis method, 1% NP-40 and protease inhibitors were added to the lysis buffers of the Paris system. Protein lysate concentrations were quantified, then purity of subcellular lysates was determined by western blotting. Histone H3 and GAPDH were used to identify nuclear and cytoplasmic compartments, respectfully.
 Results: Western blotting confirmed that adding 1% NP-40 to the lysis reagents of the AmbionTM Paris kit optimized subcellular fractionization.
 Potential Impact: Being able to efficiently separate the cytoplasmic and nuclear compartments will allow for accurate identification of NFX1-123 localization during long-term HPV16 infection. If NFX1-123 is found to move into the nucleus under the influence of HPV 16E6, then this could indicate potential transcriptional regulatory functions of the NFX1-123 protein during HPV infection, which is unique from its function in non-infected cells.

Sample Preparation for In Situ Cryotomography of Mammalian Cells.

In situ cellular cryotomography is a powerful technique for studying complex objects in their native frozen-hydrated cellular context, making it highly relevant to cellular biology and virology. The potential of combining cryotomography with other microscopy modalities makes it a perfect technique for integrative and correlative imaging. However, sample preparation for in situ cellular tomography is not straightforward, as cells do not readily attach and stretch over the electron microscopy grid. Additionally, the grids themselves are fragile and can break if handled too forcefully, resulting in the loss of imageable areas. The geometry of tissue culture dishes can also pose a challenge when manipulating the grids with tweezers. Here, we describe the tips and tricks to overcome these (and other) challenges and prepare good-quality samples for in situ cellular cryotomography and correlative imaging of adherent mammalian cells. With continued advances in cryomicroscopy technology, this technique holds enormous promise for advancing our understanding of complex biological systems.

Enhanced Expansion of Human Pluripotent Stem Cells and Somatic Cell Reprogramming Using Defined and Xeno-Free Culture Conditions.

Human embryonic stem cells and induced pluripotent stem cells (hPSC) have an unprecedented opportunity to revolutionize the fields of developmental biology as well as tissue engineering and regenerative medicine. However, their applications have been significantly limited by the lack of chemically defined and xeno-free culture conditions. The demand for the high-quality and scaled-up production of cells for use in both research and clinical studies underscores the need to develop tools that will simplify the in vitro culture process while reducing the variables. Here, we describe a systematic study to identify the optimal conditions for the initial cell attachment of hPSC to tissue culture dishes grafted with polymers of N-(3-Sulfopropyl)-N-Methacryloxyethyl-N, N-Dimethylammoniun Betaine (PMEDSAH) in combination with chemically defined and xeno-free culture media. After testing multiple supplements and chemicals, we identified that pre-conditioning of PMEDSAH grafted plates with 10% human serum (HS) supported the initial cell attachment, which allowed for the long-term culture and maintenance of hPSC compared to cells cultured on Matrigel-coated plates. Using this culture condition, a 2.1-fold increase in the expansion of hPSC was observed without chromosomal abnormalities. Furthermore, this culture condition supported a higher reprogramming efficiency (0.37% vs. 0.22%; p < 0.0068) of somatic cells into induced pluripotent stem cells compared to the non-defined culture conditions. This defined and xeno-free hPSC culture condition may be used in obtaining the large populations of hPSC and patient-derived iPSC required for many applications in regenerative and translational medicine.

RNA-Seq Analysis Reveals Altered Expression of Cell Adhesion-Related Genes Following PZR Knockout in Lung Cancer Cells.

Protein zero related (PZR) serves as a substrate and anchor protein for SHP-2, the product of the proto-oncogene PTPN11 that is frequently mutated in cancers. The expression level of PZR is elevated in various cancers, which is correlated with an unfavorable prognosis. The role of PZR in lung cancer is not fully studied. To investigate how PZR affects signaling pathways involved in LUAD development, we utilized the CRISPR technology to knock out PZR expression in SPC-A1 lung adenocarcinoma cells and then conducted RNA sequencing to profile the transcriptome. Our results showed that 226 genes exhibited differential expressions in PZR-knockout SPC-A1 cells vs wild-type cells. Many of the genes encode proteins involved in cell adhesion, migration, actin cytoskeleton organization, and regulation of cell shape. Furthermore, our experimental data showed that PZR-knockout SPC-A1 cells displayed faster attachment to tissue culture dishes and slower detachment from the dishes upon EDTA treatment. The data suggest an important role of PZR in cell-matrix interaction and may provide new insights into the signaling events that regulate cancer development.

Matrilin-2 within a three-dimensional lysine-modified chitosan porous scaffold enhances Schwann cell migration and axonal outgrowth for peripheral nerve regeneration.

Background: Matrilin-2 is a key extracellular matrix protein involved in peripheral nerve regeneration. We sought to develop a biomimetic scaffold to enhance peripheral nerve regeneration by incorporating matrilin-2 within a chitosan-derived porous scaffold. We hypothesized that the use of such a novel biomaterial delivers microenvironmental cues to facilitate Schwann cell (SC) migration and enhance axonal outgrowth during peripheral nerve regeneration. Materials and Methods: The effect of matrilin-2 on SC migration was evaluated with agarose drop migration assay on matrilin-2 coated dishes. SC adhesion was determined with SCs cultured atop tissue culture dishes coated with matrilin-2. Various formulations of chitosan vs matrilin-2 in scaffold constructs were examined with scanning electron microscopy. The effect of the matrilin-2/chitosan scaffold on SC migration in the collagen conduits was determined by capillary migration assays. Neuronal adhesion and axonal outgrowth were evaluated with three-dimensional (3D) organotypic assay of dorsal root ganglions (DRG). DRG axonal outgrowth within the scaffolds was determined by immunofluorescence staining of neurofilaments. Results: Matrilin-2 induced SC migration and enhanced its adhesion. A formulation of 2% chitosan with matrilin-2 demonstrated an optimal 3D porous architecture for SC interaction. Matrilin-2/chitosan scaffold enabled SCs to migrate against gravity within conduits. Chemical modification of chitosan with lysine (K-chitosan) further improved DRG adhesion and axonal outgrowth than the matrilin-2/chitosan scaffold without lysine modification. Conclusion: We developed a matrilin-2/K-chitosan scaffold to mimic extracellular matrix cues and provide a porous matrix to enhance peripheral nerve regeneration. Taking advantage of matrilin-2's capability to stimulate SC migration and adhesion, we formulated a porous matrilin-2/chitosan scaffold to support axongal outgrowth. Chemical modification of chitosan with lysine further improved matrilin-2 bioactivity in the 3D scaffold. The 3D porous matrilin-2/K-chitosan scaffolds have high potential for enhancing nerve repair by stimulating SC migration, neuronal adhesion, and axonal outgrowth.

Generation of Human Blood Vessel Organoids from Pluripotent Stem Cells.

An organoid is defined as an engineered multicellular in vitro tissue that mimics its corresponding in vivo organ such that it can be used to study defined aspects of that organ in a tissue culture dish. The breadth and application of human pluripotent stem cell (hPSC)-derived organoid research have advanced significantly to include the brain, retina, tear duct, heart, lung, intestine, pancreas, kidney, and blood vessels, among several other tissues. The development of methods for the generation of human microvessels, specifically, has opened the way for modeling human blood vessel development and disease in vitro and for the testing and analysis of new drugs or tissue tropism in virus infections, including SARS-CoV-2. Complex and lengthy protocols lacking visual guidance hamper the reproducibility of many stem cell-derived organoids. Additionally, the inherent stochasticity of organoid formation processes and self-organization necessitates the generation of optical protocols to advance the understanding of cell fate acquisition and programming. Here, a visually guided protocol is presented for the generation of 3D human blood vessel organoids (BVOs) engineered from hPSCs. Presenting a continuous basement membrane, vascular endothelial cells, and organized articulation with mural cells, BVOs exhibit the functional, morphological, and molecular features of human microvasculature. BVO formation is initiated through aggregate formation, followed by mesoderm and vascular induction. Vascular maturation and network formation are initiated and supported by embedding aggregates in a 3D collagen and solubilized basement membrane matrix. Human vessel networks form within 2-3 weeks and can be further grown in scalable culture systems. Importantly, BVOs transplanted into immunocompromised mice anastomose with the endogenous mouse circulation and specify into functional arteries, veins, and arterioles. The present visually guided protocol will advance human organoid research, particularly in relation to blood vessels in normal development, tissue vascularization, and disease.

Mitochondrial plasticity supports proliferative outgrowth and invasion of ovarian cancer spheroids during adhesion.

Ovarian cancer cells aggregate during or after exfoliation from the primary tumor to form threedimensional spheroids. Spheroid formation provides a survival advantage during peritoneal dissemination in nutrient and oxygen-depleted conditions which is accompanied by a suppressed metabolic phenotype and fragmented mitochondria. Upon arrival to their metastatic sites, spheroids adhere to peritoneal organs and transition to a more epithelial phenotype to support outgrowth and invasion. In this study, we investigated the plasticity of mitochondrial morphology, dynamics, and function upon adhesion. Using our slow-developing (MOSE-L) and fast-developing (MOSE-LTICv) ovarian cancer models, we mimicked adhesion and reoxygenation conditions by plating the spheroids onto tissue culture dishes and changing culture conditions from hypoxia and low glucose to normoxia with high glucose levels after adhesion. We used Western Blot, microscopy and Seahorse analyses to determine the plasticity of mitochondrial morphology and functions upon adhesion, and the impact on proliferation and invasion capacities. Independent of culture conditions, all spheroids adhered to and began to grow onto the culture plates. While the bulk of the spheroid was unresponsive, the mitochondrial morphology in the outgrowing cells was indistinguishable from cells growing in monolayers, indicating that mitochondrial fragmentation in spheroids was indeed reversible. This was accompanied by an increase in regulators of mitobiogenesis, PGC1a, mitochondrial mass, and respiration. Reoxygenation increased migration and invasion in both cell types but only the MOSE-L responded with increased proliferation to reoxygenation. The highly aggressive phenotype of the MOSE-LTICv was characterized by a relative independence of oxygen and the preservation of higher levels of proliferation, migration and invasion even in limiting culture conditions but a higher reliance on mitophagy. Further, the outgrowth in these aggressive cells relies mostly on proliferation while the MOSE-L cells both utilize proliferation and migration to achieve outgrowth. Suppression of proliferation with cycloheximide impeded aggregation, reduced outgrowth and invasion via repression of MMP2 expression and the flattening of the spheroids. Our studies indicate that the fragmentation of the mitochondria is reversible upon adhesion. The identification of regulatory signaling molecules and pathways of these key phenotypic alterations that occur during primary adhesion and invasion is critical for the identification of druggable targets for therapeutic intervention to prevent aggressive metastatic disease.

Cell Dome as an Evaluation Platform for Organized HepG2 Cells.

Human-hepatoblastoma-derived cell line, HepG2, has been widely used in liver and liver cancer studies. HepG2 spheroids produced in a three-dimensional (3D) culture system provide a better biological model than cells cultured in a two-dimensional (2D) culture system. Since cells at the center of spheroids exhibit specific behaviors attributed to hypoxic conditions, a 3D cell culture system that allows the observation of such cells using conventional optical or fluorescence microscopes would be useful. In this study, HepG2 cells were cultured in "Cell Dome", a micro-dome in which cells are enclosed in a cavity consisting of a hemispherical hydrogel shell. HepG2 cells formed hemispherical cell aggregates which filled the cavity of Cell Domes on 18 days of culture and the cells could continue to be cultured for 29 days. The cells at the center of hemispherical cell aggregates were observed using a fluorescence microscope. The cells grew in Cell Domes for 18 days exhibited higher Pi-class Glutathione S-Transferase enzymatic activity, hypoxia inducible factor-1α gene expression, and higher tolerance to mitomycin C than those cultured in 2D on tissue culture dishes (* p &lt; 0.05). These results indicate that the center of the glass adhesive surface of hemispherical cell aggregates which is expected to have the similar environment as the center of the spheroids can be directly observed through glass plates. In conclusion, Cell Dome would be useful as an evaluation platform for organized HepG2 cells.

The Role of Genetically Modified Human Feeder Cells in Maintaining the Integrity of Primary Cultured Human Deciduous Dental Pulp Cells.

Tissue-specific stem cells exist in tissues and organs, such as skin and bone marrow. However, their pluripotency is limited compared to embryonic stem cells. Culturing primary cells on plastic tissue culture dishes can result in the loss of multipotency, because of the inability of tissue-specific stem cells to survive in feeder-less dishes. Recent findings suggest that culturing primary cells in medium containing feeder cells, particularly genetically modified feeder cells expressing growth factors, may be beneficial for their survival and proliferation. Therefore, the aim of this study was to elucidate the role of genetically modified human feeder cells expressing growth factors in maintaining the integrity of primary cultured human deciduous dental pulp cells. Feeder cells expressing leukemia inhibitory factor, bone morphogenetic protein 4, and basic fibroblast growth factor were successfully engineered, as evidenced by PCR. Co-culturing with mitomycin-C-treated feeder cells enhanced the proliferation of newly isolated human deciduous dental pulp cells, promoted their differentiation into adipocytes and neurons, and maintained their stemness properties. Our findings suggest that genetically modified human feeder cells may be used to maintain the integrity of primary cultured human deciduous dental pulp cells.

Organ-specific extracellular matrix directs trans-differentiation of mesenchymal stem cells and formation of salivary gland-like organoids in vivo

BackgroundCurrent treatments for salivary gland (SG) hypofunction are palliative and do not address the underlying cause or progression of the disease. SG-derived stem cells have the potential to treat SG hypofunction, but their isolation is challenging, especially when the tissue has been damaged by disease or irradiation for head and neck cancer. In the current study, we test the hypothesis that multipotent bone marrow-derived mesenchymal stem cells (BM-MSCs) in a rat model are capable of trans-differentiating to the SG epithelial cell lineage when induced by a native SG-specific extracellular matrix (SG-ECM) and thus may be a viable substitute for repairing damaged SGs.MethodsRat BM-MSCs were treated with homogenates of decellularized rat SG-ECM for one hour in cell suspension and then cultured in tissue culture plates for 7 days in growth media. By day 7, the cultures contained cell aggregates and a cell monolayer. The cell aggregates were hand-selected under a dissecting microscope, transferred to a new tissue culture dish, and cultured for an additional 7 days in epithelial cell differentiation media. Cell aggregates and cells isolated from the monolayer were evaluated for expression of SG progenitor and epithelial cell specific markers, cell morphology and ultrastructure, and ability to form SG-like organoids in vivo.ResultsThe results showed that this approach was very effective and guided the trans-differentiation of a subpopulation of CD133-positive BM-MSCs to the SG epithelial cell lineage. These cells expressed amylase, tight junction proteins (Cldn 3 and 10), and markers for SG acinar (Aqp5 and Mist 1) and ductal (Krt 14) cells at both the transcript and protein levels, produced intracellular secretory granules which were morphologically identical to those found in submandibular gland, and formed SG-like organoids when implanted in the renal capsule in vivo.ConclusionsThe results of this study suggest the feasibility of using autologous BM-MSCs as an abundant source of stem cells for treating SG hypofunction and restoring the production of saliva in these patients.

A novel alveolar epithelial cell sheet fabricated under feeder-free conditions for potential use in pulmonary regenerative therapy.

IntroductionLung transplantation is the only effective treatment option for many patients with irreversible pulmonary injury, and the demand for lung transplantation is increasing worldwide and expected to continue to outstrip the number of available donors. Regenerative therapy with alveolar epithelial cells (AECs) holds promise as an alternative option to organ transplantation. AECs are usually co-cultured with mouse-derived 3T3 feeder cells, but the use of xenogeneic tissues for regenerative therapy raises safety concerns. Fabrication of AEC sheets under feeder-free conditions would avoid these safety issues. We describe a novel feeder-free method of fabricating AEC sheets that may be suitable for pulmonary regenerative therapy.MethodsLung tissues excised from male outbred rats or transgenic rats expressing green fluorescent protein (GFP) were finely minced and dissociated with elastase. The isolated AECs were cultured under four different feeder-free conditions according to whether a rho kinase (ROCK) inhibitor was included in the low-calcium medium (LCM) and whether the tissue culture dish was coated with recombinant laminin-511 E8 fragment (rLN511E8). The expanded cells were cultured on temperature-responsive dishes and subsequently harvested as AEC sheets. Engraftment of GFP-AEC sheets after their transplantation onto a partially resected region of the left lung was assessed in athymic rats.ResultsAECs proliferated and reached confluence when cultured in LCM containing a ROCK inhibitor on tissue culture dishes coated with rLN511E8. When both the ROCK inhibitor and rLN511E8-coated culture dish were used, the number of AECs obtained after 7 days of culture was significantly higher than that in the other three groups. Immunohistochemical analyses revealed that aquaporin-5, surfactant protein (SP)-A, SP-C, SP-D and Axin-2 were expressed by the cultured AECs. AEC sheets were harvested successfully from temperature-responsive culture dishes (by lowering the temperature) when the expanded AECs were cultured for 7 days in LCM + ROCK inhibitor and then for 3 days in LCM + ROCK inhibitor supplemented with 200 mg/L calcium chloride. The AEC sheets were firmly engrafted 7 days after transplantation onto the lung defect and expressed AEC marker proteins.ConclusionsAEC sheets fabricated under feeder-free conditions retained the features of AECs after transplantation onto the lung in vivo. Further improvement of this technique may allow the bioengineering of alveolar-like tissue for use in pulmonary regenerative therapy.

ER+ Breast Cancer Mammosphere Formation and Analysis.

Mammosphere formation assays are a popular and convenient technique in the study of breast cancer by providing an in vitro mechanism by which to study breast cancer stem cell (BCSC) contribution to tumorigenesis, as well as more closely mimicking the three-dimensional tumor microenvironment. In these assays, BCSCs are stimulated to proliferate in low adherence tissue culture dishes and the resulting mammospheres exhibit activation of stem cell-related signaling pathways. Here we describe the process for generating and analyzing mammospheres under varying conditions.

Cultivation of hierarchical 3D scaffolds inside a perfusion bioreactor: scaffold design and finite-element analysis of fluid flow

The use of porous 3D scaffolds for the repair of bone nonunion and osteoporotic bone is currently an area of great interest. Using a combination of thermally-induced phase separation (TIPS) and 3D-plotting (3DP), we have generated hierarchical 3DP/TIPS scaffolds made of poly(lactic-co-glycolic acid) (PLGA) and nanohydroxyapatite (nHA). A full factorial design of experiments was conducted, in which the PLGA and nHA compositions were varied between 6‒12% w/v and 10‒40% w/w, respectively, totaling 16 scaffold formulations with an overall porosity ranging between 87%‒93%. These formulations included an optimal scaffold design identified in our previous study. The internal structures of the scaffolds were examined using scanning electron microscopy and microcomputed tomography. Our optimal scaffold was seeded with MC3T3-E1 murine preosteoblastic cells and subjected to cell culture inside a tissue culture dish and a perfusion bioreactor. The results were compared to those of a commercial CellCeram™ scaffold with a composition of 40% β-tricalcium phosphate and 60% hydroxyapatite (β-TCP/HA). Media flow within the macrochannels of 3DP/TIPS scaffolds was modeled in COMSOL software in order to fine tune the wall shear stress. CyQUANT DNA assay was performed to assess cell proliferation. The normalized number of cells for the optimal scaffold was more than twofold that of CellCeram™ scaffold after two weeks of culture inside the bioreactor. Despite the substantial variability in the results, the observed improvement in cell proliferation upon culture inside the perfusion bioreactor (vs. static culture) demonstrated the role of macrochannels in making the 3DP/TIPS scaffolds a promising candidate for scaffold-based tissue engineering.

Evaluating Mouse Fibroblast Interaction with Implant Surfaces in a 3D Microenvironment

Previous studies assessing fibroblast interactions with implants have mainly relied on measurements such as cell migration, gene expression, and cell adhesion. For these studies, testing cellular behavior at the implant surface was done by imaging the cell-implant interface using standard microscopy techniques in 2D tissue culture dishes. The true behavior of cells relative to the implant can best be assessed in a more physiologic 3D microenvironment. The embedding of the implant disks in 3D collagen gels was standardized with labeled fibroblasts to allow the imaging of fibroblast morphology and behavior when proximal to or binding to the implant disks. This allowed comparison of the behavior of laser-microgrooved and machined implant disk surfaces quantitatively in an in vitro 3D microenvironment. This in vitro imaging assay revealed for the first time in a 3D microenvironment setting the statistically significant impact laser-microgrooved disk surfaces have on both cell adherence and recruitment of cells in proximity to the disk. It also allowed visualization of membrane protrusivity and cytoskeletal organization in cells adherent to the implant disk. This assay provides a simple and effective way of observing cell behavior on and around the implant disk surface in a more physiologic 3D setting. Within the limits of this study, it revealed that the laser-microgrooved implant surface demonstrates significant superiority in fibroblast recruitment and binding in a 3D microenvironment.

Abstract P383: 3D-collagen Matrix Enhanced Integrins And Matrix Metalloproteinases Expression In Cardiac Mesenchymal Cells

Introduction: Use of cardiac mesenchymal cells (CMCs) has been shown to improve cardiac function following myocardial infarction. Main drawback in cardiac cell therapy is the major loss of injected cells within few hours. Increase the retention of these injected cells could increase their efficacy, where cardiac patches with various cell types showed better outcome. Among, collagen patch plays lead role as a cell-laden matrix in cardiac tissue engineering. Creating a detailed understanding of how collagen matrix changes the cellular phenotype could provide seminal insights to regeneration therapy. Hypothesis: Growing CMCs in three dimensional (3D) collagen matrix could alter the expression of extracellular matrix (ECM) and adhesion molecules, which may enhance their efficacy. Methods: The bovine type I collagen was chemically modified and solubilized in culture medium with photo-initiator. The mouse CMCs were isolated and resuspended in collagen solution, printed using 3D bioprinter and UV-crosslinked to form 3D-CMC construct. The 3D-CMC construct was submerged in growth medium and cultured for 48h and analyzed for the expression of ECM and adhesion molecules (n=5/group). CMCs cultured in regular plastic tissue culture dish was used as control. Results: RT profiler array showed changes in the ECM and adhesion molecules expression, specifically certain integrins and matrix metalloproteinases (MMPs) in CMCs cultured 3D collagen construct compared to 2D monolayer. Subsequent qRT-PCR analysis revealed significant (p&lt;0.01) upregulation of integrins such as Itga2 (2.96±0.13), Itgb1 (3.18±0.2) and Itgb3 (2.4±0.27) and MMPs such as MMP13 (37.2±3.36), MMP9 (5.23±1.06) and MMP3 (7.14±2.07). Western blot analysis further confirmed significant elevation of these integrins and matrix metalloproteinases at protein level. Collagen encapsulation did not alter the expression of N-cadherin in CMCs, which is a potential mesenchymal cadherin adhesion molecule. Conclusion: Integrin αβ heterodimers transduce signals that facilitate cell homing, migration, survival and differentiation. Similarly, MMPs plays vital role in cell migration and proliferation. Our results demonstrate that the 3D-collagen Niche enhances the expression of certain integrins and MMPs in CMCs. This suggest that the efficacy of CMCs could be magnified by providing 3D architecture with collagen matrix and further in vivo experiments would reveal functional benefits from CMCs for clinical use.

Protective Effects of a Hyaluronan-Binding Peptide (P15-1) on Mesenchymal Stem Cells in an Inflammatory Environment.

Mesenchymal stem cells (MSCs) obtained from various sources, including bone marrow, have been proposed as a therapeutic strategy for the improvement of tissue repair/regeneration, including the repair of cartilage defects or lesions. Often the highly inflammatory environment after injury or during diseases, however, greatly diminishes the therapeutic and reparative effectiveness of MSCs. Therefore, the identification of novel factors that can protect MSCs against an inflammatory environment may enhance the effectiveness of these cells in repairing tissues, such as articular cartilage. In this study, we investigated whether a peptide (P15-1) that binds to hyaluronan (HA), a major component of the extracellular matrix of cartilage, protects bone-marrow-derived MSCs (BMSCs) in an inflammatory environment. The results showed that P15-1 reduced the mRNA levels of catabolic and inflammatory markers in interleukin-1beta (IL-1β)-treated human BMSCs. In addition, P15-1 enhanced the attachment of BMSCs to HA-coated tissue culture dishes and stimulated the chondrogenic differentiation of the multipotential murine C3H/10T1/2 MSC line in a micromass culture. In conclusion, our findings suggest that P15-1 may increase the capacity of BMSCs to repair cartilage via the protection of these cells in an inflammatory environment and the stimulation of their attachment to an HA-containing matrix and chondrogenic differentiation.