Aggregate Cultures Research Articles

Construction of bioengineered hepatic tissue derived from human umbilical cord mesenchymal stem cells via aggregation culture in porcine decellularized liver scaffolds.

An individualized, tissue-engineered liver suitable for transplanting into a patient with liver disease would be of great benefit to the patient and the healthcare system. The tissue-engineered liver would possess the functions of the original healthy organ. Two fields of study, (i) using decellularized tissue as cell scaffolding, and (ii) stem cell differentiation into functional cells, are coming together to make this concept feasible. The decellularized liver scaffolds (DLS) can interact with cells to promote cell differentiation and signal transduction and three-dimensional (3D) stem cell aggregations can maintain the phenotypes and improve functions of stem cells after differentiation by undergoing cell-cell contact. Although the effects of DLS and stem cell aggregation culture have been intensively studied, few observations about the interaction between the two have been achieved. We established a method that combines the use of decellularized liver scaffolds and aggregation culture of MSCs (3D-DLS) and explored the effects of the two on hepatic differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) in bioengineered hepatic tissue. A higher percentage of albumin-producing cells, higher levels of liver-specific transcripts, higher urea cycle-related transcripts, and lower levels of stem cell-specific transcripts were observed in the 3D-DLS group when compared to that of hUC-MSCs in monolayer culture (2D), aggregation culture (3D), monolayer on DLS culture (2D-DLS). The gene arrays also indicated that 3D-DLS induced the differentiation from the hUC-MSC phenotype to the PHH phenotype. Liver-specific proteins albumin, CK-18, and glycogen storage were highly positive in the 3D-DLS group. Albumin secretion and ammonia conversion to urea were more effective with a higher cell survival rate in the 3D-DLS group for 14days. This DLS and aggregation combination culture system provides a novel method to improve hepatic differentiation, maintain phenotype of hepatocyte-like cells and sustain survival for 14days in vitro. This is a promising strategy to use to construct bioengineered hepatic tissue.

Immunogenicity of hepatic differentiated human umbilical cord mesenchymal stem cells promoted by porcine decellularized liver scaffolds.

Cell-based approaches, including hepatocyte transplantation and tissue-engineered livers, offer promising alternatives and are expected to help support patients with liver diseases until liver transplantation or recovery via regeneration of the damaged liver. However, the success of cell therapies remains dependent on how well the cells are accepted after transplantation and is directly related to their degree of immunogenicity. In this study, hepatic differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) was induced in the traditional monolayer (2D) culture and newly established three-dimensional (3D) aggregation culture with the porcine decellularized liver scaffold (DLS) system (3D-DLS). We investigated the immunogenicity of these hepatocyte-like cells in vitro. We found that monolayer hepatic differentiated hUC-MSCs expressed higher levels of human leukocyte antigen-DR (HLA-DR) (P<.05) and lost the ability to inhibit lymphocyte proliferation (P<.05), in association with a lower level of prostaglandin E2 (PGE2 ) (P<.05) and a higher level of interferon-γ (IFN-γ) (P<.05) secretion, compared to undifferentiated hUC-MSCs. The hepatocyte-like cells differentiated in the 3D-DLS system did not show an elevation of MHC-II (P>.05), or cause obvious lymphocytes proliferation, and demonstrated more PGE2 (P<.05) and less IFN-γ (P<.05) secretion. Hepatocyte-like cells in the 3D-DLS system presented a lower immunogenic phenotype than the 2D culture in vitro. Hepatocyte-like cells in 3D-DLS system also performed a higher immunosuppressive capacity than 2D culture.

A microfluidic trap array for longitudinal monitoring and multi-modal phenotypic analysis of individual stem cell aggregates.

Three-dimensional pluripotent stem cell (PSC) cultures have the ability to undergo differentiation, self-organization, and morphogenesis to yield complex, in vitro tissue models that recapitulate key elements of native tissues. These tissue models offer a system for studying mechanisms of tissue development, investigating disease mechanisms, and performing drug screening. It remains challenging, however, to standardize PSC aggregate differentiation and morphogenesis methods due to heterogeneity stemming from biological and environmental sources. It is also difficult to monitor and assess large numbers of individual samples longitudinally throughout culture using typical batch-based culture methods. To address these challenges, we have developed a microfluidic platform for culture, longitudinal monitoring, and phenotypic analysis of individual stem cell aggregates. This platform uses a hydrodynamic loading principle to capture pre-formed stem cell aggregates in independent traps. We demonstrated that multi-day culture of aggregates in this platform reduces heterogeneity in phenotypic parameters such as size and morphology. Additionally, we showed that culture and analysis steps can be performed sequentially in the same platform, enabling correlation of multiple modes of analysis for individual samples. We anticipate this platform being applied to improve abilities for phenotypic analysis of PSC aggregate tissues and to facilitate research in standardizing culture systems in order to dually increase the yield and reduce the heterogeneity of PSC-derived tissues.

Controlled production of sub-millimeter liquid core hydrogel capsules for parallelized 3D cell culture.

Liquid core capsules having a hydrogel membrane are becoming a versatile tool for three-dimensional culture of micro-organisms and mammalian cells. Making sub-millimeter capsules at a high rate, via the breakup of a compound jet in air, opens the way to high-throughput screening applications. However, control of the capsule size monodispersity, especially required for quantitative bioassays, was still lacking. Here, we report how the understanding of the underlying hydrodynamic instabilities that occur during the process can lead to calibrated core-shell bioreactors. The requirements are: i) damping the shear layer instability that develops inside the injector arising from the co-annular flow configuration of liquid phases having contrasting viscoelastic properties; ii) controlling the capillary instability of the compound jet by superposing a harmonic perturbation onto the shell flow; iii) avoiding coalescence of drops during jet fragmentation as well as during drop flight towards the gelling bath; iv) ensuring proper engulfment of the compound drops into the gelling bath for building a closed hydrogel shell. We end up with the creation of numerous identical compartments in which cells are able to form multicellular aggregates, namely spheroids. In addition, we implement an intermediate composite hydrogel layer, composed of alginate and collagen, allowing cell adhesion and thus the formation of epithelia or monolayers of cells.

Electrospun polystyrene scaffolds as a synthetic substrate for xeno-free expansion and differentiation of human induced pluripotent stem cells

To realize the potential of human induced pluripotent stem cells (hiPSCs) in clinical medicine, robust, xeno-free substrates for expansion and differentiation of iPSCs are required. In the existing literature, synthetic materials have been reported that meet the requirement for non-xenogeneic substrates. However, the self-renewal and differentiation characteristics of hiPSCs are affected differently by the biocompatibility and physico-chemical properties of individual substrates. Although some rules based on chemical structure and substrate rigidity have been developed, most of these efforts are still empirical, and most synthetic substrates must still be rigorously screened for suitability. In this paper, we demonstrate an alternative concept for xeno-free expansion and differentiation of hiPSCs using synthetic substrates, which hinges on the structure-function relationship between electrospun polystyrene scaffolds (ESPS) and pluripotent stem cell growth. ESPS of differential porosity was obtained by fusing the fibers at different temperatures. The more porous, loosely fused scaffold was found to efficiently trap the cells, leading to a large number of three-dimensional (3D) aggregates. In the form of these trapped aggregates, we showed that hiPSCs could be cultured for up to 10 consecutive passages (P10) with maintenance of pluripotency, following which they could be differentiated to a chosen lineage. We believe that this novel, generic class of synthetic substrates that employs 'trapped aggregate culture' for expansion and differentiation of hiPSCs is an important conceptual advance, and would be of high interest to the readership of Acta Biomaterialia.

Effects of passage number and post-expansion aggregate culture on tissue engineered, self-assembled neocartilage.

Chondrocyte dedifferentiation presents a major barrier in engineering functional cartilage constructs. To mitigate the effects of dedifferentiation, this study employed a post-expansion aggregate culture step to enhance the chondrogenic phenotype of passaged articular chondrocytes (ACs) before their integration into self-assembled neocartilage constructs. The objective was twofold: (1) to explore how passage number (P2, P3, P4, P5, P6, and P7), with or without aggregate culture, affected construct properties; and (2) to determine the highest passage number that could form neocartilage with functional properties. Juvenile leporine ACs were passaged to P2-P7, with or without aggregate culture, and self-assembled into 5mm discs in non-adhesive agarose molds without using any exogenous scaffolds. Construct biochemical and biomechanical properties were assessed. With aggregate culture, neocartilage constructs had significantly higher collagen content, higher tensile properties, and flatter morphologies. These beneficial effects were most obvious at higher passage numbers. Specifically, collagen content, Young's modulus, and instantaneous compressive modulus in the P7, aggregate group were 53%, 116%, and 178% higher than those in the P7, non-aggregate group. Most interestingly, these extensively passaged P7 ACs (expansion factor of 85,000), which are typically highly dedifferentiated, were able to form constructs with properties similar to or higher than those formed by lower passage number cells. This study not only demonstrated that post-expansion aggregate culture could significantly improve the properties of self-assembled neocartilage, but also that chondrocytes of exceedingly high passage numbers, expanded using the methods in this study, could be used in cartilage engineering applications. This work demonstrated that extensively passaged chondrocytes (up to passage 7 (P7); expansion factor of 85,000) could potentially be used for cartilage tissue engineering applications. Specifically, an aggregate culture step, employed after cell expansion and before cell integration into a neocartilage construct, was shown to enhance the ability of the chondrocytes to form neocartilage with better biochemical and biomechanical properties. The beneficial effects of this aggregate culture step was especially noticeable at the high passage numbers. Most interestingly, P7 chondrocytes, which are typically highly dedifferentiated, were able to form neocartilage with properties similar to or higher than those formed by lower passage number cells. The ability to obtain high chondrocyte yields with an enhanced chondrogenic potential could have a broad, beneficial impact in improving current therapies (e.g., using higher cell seeding densities for repair) or developing new strategies that require high cell numbers, such as a scaffold-free approach in forming engineered cartilage.

The Effect of Underwater Blast on Aggregating Brain Cell Cultures.

Although the deleterious effects of primary blast on gas-filled organs are well accepted, the effect of blast-induced shock waves on the brain is less clear because of factors that complicate the interpretation of clinical and experimental data. Brain cell aggregate cultures are comprised of multiple differentiated brain cell types and were used to examine the effects of underwater blast. Suspensions of these cultures encased in dialysis tubing were exposed to explosive-generated underwater blasts of low (∼300 kPa), medium (∼2,700 kPa), or high (∼14,000 kPa) intensities and harvested at 1-28 days post-exposure. No changes in gross morphology were noted immediately or weeks after blast wave exposure, and no increases in either apoptotic (caspase-3) or necrotic (lactate dehydrogenase) cell death were observed. Changes in neuronal (neurofilament H, acetylcholinesterase, and choline acetyltransferase) and glial (glial fibrillary acidic protein, glutamine synthetase) endpoints did not occur. However, significant time- and pressure-related increases in Akt (protein kinase B) phosphorylation were noted, as well as declines in vascular endothelial growth factor levels, implicating pathways involved in cellular survival mechanisms. The free-floating nature of the aggregates during blast wave exposure, coupled with their highly hydrolyzed dialysis tubing containment, results in minimized boundary effects, thus enabling accurate assessment of brain cell response to a simplified shock-induced stress wave. This work shows that, at its simplest, blast-induced shock waves produce subtle changes in brain tissue. This study has mechanistic implications for the study of primary blast-induced traumatic brain injury and supports the thesis that underwater blast may cause subtle changes in the brains of submerged individuals.

Enhanced hepatic differentiation of rat bone marrow-derived mesenchymal stem cells in spheroidal aggregate culture on a decellularized liver scaffold.

In the present study, we aimed to determine whether the combination of aggregate culture and decellularized liver scaffolds (DLSs) promoted the hepatic differentiation of murine bone marrow-derived mesenchymal stem cells (BM-MSCs) into high yields of mature hepatocytes in vitro. Four culturing methods for differentiation [single cell (2D), spheroids (3D), 2D + DLS and 3D + DLS] were studied. To determine the differentiation stages of the MSCs, RT-qPCR of the hepatocyte genes, immunostaining of hepatocyte markers, and functional analyses were all performed. Compared with the other groups, hepatocyte-like cells which differentiated from BM-MSC spheroids on extracellular matrix (ECM) exhibited more intensive staining of stored glycogen, an elevated level of urea biosynthesis and albumin secretion as well as the higher expression of hepatocyte-specific genes. Our results indicated that DLSs combined with spheroidal aggregate culture may be used as an effective method to facilitate the hepatic maturation of BM-MSCs and may have future applications in stem cell-based liver regenerative medicine.

Cells Cultured on Core-Shell Photonic Crystal Barcodes for Drug Screening.

The development of effective drug screening platforms is an important task for biomedical engineering. Here, a novel methacrylated gelatin (GelMA) hydrogel-encapsulated core-shell photonic crystal (PhC) barcode particle was developed for three-dimensional cell aggregation culture and drug screening. The GelMA shells of the barcode particles enable creation of a three-dimensional extracellular matrix (ECM) microenvironment for cell adhesion and growth, while the PhC cores of the barcode particles provide stable diffraction peaks that can encode different cell spheroids during culture and distinguish their biological response during drug testing. The applicability of this cell spheroids-on-barcodes platform was investigated by testing the cytotoxic effect of tegafur (TF), a prodrug of 5-fluorouracil (5-FU), on barcode particle-loaded liver HepG2 and HCT-116 colonic tumor cell spheroids. The cytotoxicity of TF against the HCT-116 tumor cell spheroids was enhanced in systems using cocultures of HepG2 and NIH-3T3 cells, indicating the effectiveness of this multiple cell spheroids-on-barcodes platform for drug screening.

Reproducible preparation of spheroids of pancreatic hormone positive cells from human iPS cells: An in vitro study

BackgroundTransplantation of islets of Langerhans is regarded as a promising therapy for type 1 diabetes. A large number of β-cells are required for the treatment of human type 1 diabetes. Pluripotent stem cells, such as embryonic stem cells and induced pluripotent stem cells, have been considered as new sources for cell replacement therapy. MethodsCell aggregates were prepared from human iPS cells using agarose microwell plates and differentiated into pancreatic endocrine cells by changing the culture media with different additives. ResultsAfter 20days of culture, approximately 30% of cells in aggregates were positive for C-peptide. After another 14days in culture, the cells gained an ability to alter C-peptide release in response to changes in the glucose concentration. ConclusionsUniform aggregates of human iPSCs were easily prepared on agarose microwell plates and efficiently differentiated into the pancreatic endocrine lineage. Thus, aggregate culture is a suitable method for preparing islet-like aggregates from human iPSCs. General significanceOur results indicate that the microwell plate is suitable for scaling up the preparation of pancreatic endocrine cells from human iPS cells in a robotic system.

444. Large Scale Culture and Differentiation of Induced Pluripotent Stem Cells for Neutrophil Replacement Therapies

Neutrophils are a key component in the innate immune system and are crucial in the protection against bacterial and fungal infections. Patients with neutropenias are at high risk to develop serious life threatening bacterial and fungal infections. Transfusion of donor neutrophils into neutropenic patients may help alleviate disease burden, but difficulty in collecting and transfusing sufficient quantities of viable donor neutrophils has limited the clinical adaptation of neutrophil replacement therapies. Induced pluripotent stem cells (iPSC) are an attractive alternative source to donor derived neutrophils due to their ability to self-renew and differentiate into cells of the three embryonic germ layers, including neutrophils. Successful implementation of iPSC for neutrophil replacement therapies will require a) derivation of iPSC, b) large scale culture of iPSC, and c) efficient differentiation of these iPSC into functional neutrophils in xeno-fee, GMP-compliant conditions. First, normal human fibroblasts were reprogrammed in xeno-free, GMP compliant conditions though nucleofection of a non-integrating 3 plasmid system carrying OCT4, SOX2, KLF-4, l-MYC, Lin28 and shp53. The reprogrammed fibroblasts were cultured in defined conditions on Vitronectin XF in TeSR-E7 media until colony formation when they were transitioned to E8 medium. We generated 3 lines under these conditions and all iPSC derived and cultured under these conditions retain a normal karyotype, express pluripotency markers SSEA-4, Tra-1-60, Tra-1-81, and CD9 at >85% as determined by FACs analysis, and differentiate into all three germ layers in vitro. Once iPSC lines were established, cultures were adapted from adherent cultures to non-adherent, aggregate suspension cultures in spinner flask bioreactor systems in mTeSR or E8 medium. Briefly, adherent iPSC are dissociated into single cells and seeded into a spinner flask at a concentration of 2×105 cells/ml and spun at 60 RPM. We evaluated 2 lines in 3 independent experiments and cells readily formed clusters and were able to achieve 4-log expansion (range: 2-4 log) within approximately 40 days (10 passages). All lines retained a normal karyotype, expressed pluripotency markers SSEA-4, Tra-1-60, Tra-1-81, and CD9 (>85%), and displayed a normal morphology when re-plated in adherent culture. We next adapted a neutrophil differentiation system for differentiation from iPSC from the defined media/spinnerflask system. Clusters of cells from spinner flask cultures were induced to form embryoid bodies (EBs) by transitioning the cultures to EB specification medium for 5 days, followed by a neutrophil specification medium containing IL-3 and G-CSF in adherent conditions. After 7-14 days in neutrophil specification conditions, EBs attached to the plate and CD45+CD11b+CD16+ neutrophils were shed into the medium and were harvested twice weekly for 30-60 days. In 10 experiments, we collected an average of 6.5×10^5 CD45+ cells per well of differentiation representing a 6.5 fold expansion (range: 3-10 fold). In conclusion, iPSC have been derived in GMP compliant conditions and can be cultured at a large scale using spinner flask bioreactors, and the iPSC from spinner flask bioreactors can then successfully be differentiated into CD45+ cells. Thus, iPSC represent an attractive, self-renewing resource of neutrophils for neutrophil replacement therapies.

Disparate response of articular- and auricular-derived chondrocytes to oxygen tension

ABSTRACTPurpose/Aim: To determine the effect of reduced (5%) oxygen tension on chondrogenesis of auricular-derived chondrocytes. Currently, many cell and tissue culture experiments are performed at 20% oxygen with 5% carbon dioxide. Few cells in the body are subjected to this supra-physiological oxygen tension. Chondrocytes and their mesenchymal progenitors are widely reported to have greater chondrogenic expression when cultured at low, more physiological, oxygen tension (1–7%). Although generally accepted, there is still some controversy, and different culture methods, species, and outcome metrics cloud the field. These results are, however, articular chondrocyte biased and have not been reported for auricular-derived chondrocytes. Materials and Methods: Auricular and articular chondrocytes were isolated from skeletally mature New Zealand White rabbits, expanded in culture and differentiated in high density cultures with serum-free chondrogenic media. Cartilage tissue derived from aggregate cultures or from the tissue engineered sheets were assessed for biomechanical, glycosaminoglycan, collagen, collagen cross-links, and lysyl oxidase activity and expression. Results: Our studies show increased proliferation rates for both auricular and articular chondrocytes at low (5%) O2 versus standard (20%) O2. In our scaffold-free chondrogenic cultures, low O2 was found to increase articular chondrocyte accumulation of glycosaminoglycan, but not cross-linked type II collagen, or total collagen. Conversely, auricular chondrocytes accumulated less glycosaminoglycan, cross-linked type II collagen and total collagen under low oxygen tension. Conclusions: This study highlights the dramatic difference in response to low O2 of chondrocytes isolated from different anatomical sites. Low O2 is beneficial for articular-derived chondrogenesis but detrimental for auricular-derived chondrogenesis.

WNT-C59, a Small-Molecule WNT Inhibitor, Efficiently Induces Anterior Cortex That Includes Cortical Motor Neurons From Human Pluripotent Stem Cells

The recapitulation of human neural development in a controlled, defined manner from pluripotent stem cells (PSCs) has considerable potential for studies of human neural development, circuit formation and function, and the construction of in vitro models of neurological diseases. The inhibition of Wnt signaling, often by the recombinant protein DKK1, is important for the induction of cortical neurons. Here, we report a novel differentiation method using a small-molecule WNT inhibitor, WNT-C59 (C59), to efficiently induce human anterior cortex. We compared two types of small molecules, C59 and XAV939 (XAV), as substitutes for DKK1 to induce cortical neurons from PSCs in serum-free embryoid body-like aggregate culture. DKK1 and XAV inhibited only the canonical pathway of Wnt signaling, whereas C59 inhibited both the canonical and noncanonical pathways. C59 efficiently induced CTIP2+/COUP-TF1- cells, which are characteristic of the cells found in the anterior cortex. In addition, when grafted into the cortex of adult mice, the C59-induced cells showed abundant axonal fiber extension toward the spinal cord. These results raise the possibility of C59 contributing to cell replacement therapy for motor neuron diseases or insults. For a cell therapy against damaged corticospinal tract caused by neurodegenerative diseases or insults, cortical motor neurons are needed. Currently, their induction from pluripotent stem cells is considered very promising; however, an efficient protocol to induce motor neurons is not available. For efficient induction of anterior cortex, where motor neurons are located, various WNT inhibitors were investigated. It was found that one of them could induce anterior cortical cells efficiently. In addition, when grafted into the cortex of adult mice, the induced cells showed more abundant axonal fiber extension toward spinal cord. These results raise the possibility that this inhibitor contributes to a cell-replacement therapy for motor neuron diseases or insults.

Lines of Descent: W.E.B. Du Bois and the Emergence of Identity

Lines of Descent: W.E.B. Du Bois and the Emergence of Identity

Co-overexpression of TGF-β and SOX9 via rAAV gene transfer modulates the metabolic and chondrogenic activities of human bone marrow-derived mesenchymal stem cells.

BackgroundArticular cartilage has a limited potential for self-healing. Transplantation of genetically modified progenitor cells like bone marrow-derived mesenchymal stem cells (MSCs) is an attractive strategy to improve the intrinsic repair capacities of damaged articular cartilage.MethodsIn this study, we examined the potential benefits of co-overexpressing the pleiotropic transformation growth factor beta (TGF-β) with the cartilage-specific transcription factor SOX9 via gene transfer with recombinant adeno-associated virus (rAAV) vectors upon the biological activities of human MSCs (hMSCs). Freshly isolated hMSCs were transduced over time with separate rAAV vectors carrying either TGF-β or sox9 in chondrogenically-induced aggregate cultures to evaluate the efficacy and duration of transgene expression and to monitor the effects of rAAV-mediated genetic modification upon the cellular activities (proliferation, matrix synthesis) and chondrogenic differentiation potency compared with control conditions (lacZ treatment, sequential transductions).ResultsSignificant, prolonged TGF-β/sox9 co-overexpression was achieved in chondrogenically-induced hMSCs upon co-transduction via rAAV for up to 21 days, leading to enhanced proliferative, biosynthetic, and chondrogenic activities relative to control treatments, especially when co-applying the candidate vectors at the highest vector doses tested. Optimal co-administration of TGF-β with sox9 also advantageously reduced hypertrophic differentiation of the cells in the conditions applied here.ConclusionThe present findings demonstrate the possibility of modifying MSCs by combined therapeutic gene transfer as potent future strategies for implantation in clinically relevant animal models of cartilage defects in vivo.

Dendritic Cells Enhance HIV Infection of Memory CD4(+) T Cells in Human Lymphoid Tissues.

Dendritic cells (DCs) play a key role in controlling infections by coordinating innate and adaptive immune responses to invading pathogens. Paradoxically, DCs can increase HIV-1 dissemination in vitro by binding and transferring infectious virions to CD4(+) T cells, a process called transinfection. Transinfection has been well characterized in cultured cell lines and circulating primary T cells, but it is unknown whether DCs enhance infection of CD4(+) T cells in vivo. In untreated HIV infection, massive CD4(+) T-cell infection and depletion occur in secondary lymphoid tissues long before decline is evident in the peripheral circulation. To study the role of DCs in HIV infection of lymphoid tissues, we utilized human tonsil tissues, cultured either as tissue blocks or as aggregate suspension cultures, in single-round infection experiments. In these experiments, addition of monocyte-derived DCs (MDDCs) to the cultures increased T-cell infection, particularly in CD4(+) T cells expressing lower levels of HLA-DR. Subset analysis demonstrated that MDDCs increased HIV-1 infection of central and effector memory T-cell populations. Depletion of endogenous myeloid DCs (myDCs) from the cultures decreased memory T-cell infection, and readdition of MDDCs restored infection to predepletion levels. Using an HIV-1 fusion assay, we found that MDDCs equally increased HIV delivery into naïve, central, and effector memory T cells in the cultures, whereas predepletion of myDCs reduced fusion into memory T cells. Together, these data suggest that resident myDCs facilitate memory T-cell infection in lymphoid tissues, implicating DC-mediated transinfection in driving HIV dissemination within these tissues in untreated HIV/AIDS.

Evaluation of cell aggregation induced peptide for 3D culture

Event Abstract Back to Event Evaluation of cell aggregation induced peptide for 3D culture Yoshiaki Hirano1*, Yudai Futaki1* and Sachiro Kakinoki1* 1 Kansai University, Faculty of Chemistry, Materials and Bioengineering, Japan Introduction: Most cells within the human body interact with neighboring cells and extracellular matrix (ECM) components to establish a unique three-dimensional (3D) organization. These cell-cell and cell-ECM interactions form a complex communication network of biochemical and mechanical signals that are critical for normal cell physiology. The behavior of cells in a 3D environment is fundamentally different from that of cells in monolayer culture, however. For instance, both primary articular chondrocytes and hepatocytes rapidly lose their normal phenotype once taken out of the body and placed in two-dimensional (2D) cell culture, but this loss can be attenuated or even reversed using 3D culturing methodologies[1]-[3]. Aggregation can affect cell-cell interactions, resulting in enhanced biological functions. Conventional cell culture involves the use of 2D systems, which differ significantly from the local environment of cells in living tissues. Therefore, 3D cell culture technologies have been developed. However, when a cell aggregate becomes too large, the cells inside the aggregate tend to die due to a lack of oxygen and nutrients. Such conditions often make it difficult to culture cells in vitro for long periods of time, thereby impeding basic research into cell differentiation and organization. The periodic peptide induces the formation of fibroblast[4], hepatocyte, human mesenchymal stem cell (hMSC) aggregates. In the present study, we evaluated (Lys-Pro)12 [KP24] derivative periodic peptides, such as (Lys-Pro-Pro)8[KPP24] and (Lys-Lys-Pro)8[KKP24], with respect to the relationship between the structure of the peptide chain and the function of hepatocyte, and hMSC aggregates. Materials and Methods: Four different periodic peptides were synthesized using a solid phase peptide synthesis procedure. All peptides were characterized by HPLC, MADI-TOF-MS, and amino acid analysis. The effect of the periodic peptides on cell aggregation was evaluated using albumin production of hepatocyte, and differentiation activity of hMSC for osteogenesis. Results and Discussion: IIn the presence of peptide in cell culture medium, cell aggregation was observed beginning on the third day of culture, and the cell aggregations formed maintained their shape over the 7-day culture period. The KP24, and KPP24 peptides induced the formation of uniformly sized cell aggregates. Albumin is regarded as a key biomarker of mature hepatocytes. Albumin production was comparable in cell aggregation and 2D monolayer cultures on day 1, increased dramatically on day 3, and maintained in a relatively stable level from day 3 to 7 in both cultures. Four types periodic peptides induced cell aggregation exhibited a relatively higher albumin production with the 2D monolayer. Results of ALP activity about hMSC were presented on the day. Conclusions: Periodic peptides induced cell aggregation exhibited a relatively higher albumin production activity with the 2D monolayer on hepatocyte. This result was applied for drug metabolism, cell transplantation and micro array. This work was partly supported Grant-in-Aid for Scientific Research (C)「KAKENHI-25350556」from Japan Society for the Promotion of Science (JSPS)

Expression of BMP and Actin Membrane Bound Inhibitor Is Increased during Terminal Differentiation of MSCs.

Chondrogenic differentiating mesenchymal stem cells (MSCs) are mimicking embryonal endochondral ossification and become hypertrophic. BMP (bone morphogenetic protein) and Activin Membrane Bound Inhibitor (BAMBI) is a pseudoreceptor that regulates the activity of transforming growth factor-β (TGF-β) and BMP signalling during chondrogenesis. Both TGF-β and BMP signalling are regulators of chondrogenic cell differentiation. Human bone marrow derived MSCs were chondrogenically predifferentiated in aggregate culture for 14 days. Thereafter, one group was subjected to hypertrophy enhancing media conditions while controls were kept in chondrogenic medium until day 28. Histological evaluation, gene expression by PCR, and Western blot analysis were carried out at days 1, 3, 7, 14, 17, 21, and 28. A subset of cultures was treated with the BMP inhibitor Noggin to test for BMP dependent expression of BAMBI. Hypertrophic differentiated pellets showed larger cells with increased collagen 10 and alkaline phosphatase staining. There was significantly increased expression of BAMBI on gene expression and protein level in hypertrophic cultures compared to the chondrogenic control and increased BMP4 gene expression. Immunohistochemistry showed intense staining of BAMBI in hypertrophic cells. BAMBI expression was dose-dependently downregulated by Noggin. The pseudoreceptor BAMBI is upregulated upon enhancement of hypertrophy in MSC chondrogenic differentiation by a BMP dependent mechanism.

Aggregate formation and suspension culture of human pluripotent stem cells and differentiated progeny

Culture of human pluripotent stem cells (hPSC) as in vitro multicellular aggregates has been increasingly used as a method to model early embryonic development. Three-dimensional assemblies of hPSCs facilitate interactions between cells and their microenvironment to promote morphogenesis, analogous to the multicellular organization that accompanies embryogenesis. In this paper, we describe a method for reproducibly generating and maintaining populations of homogeneous three-dimensional hPSC aggregates using forced aggregation and rotary orbital suspension culture. We propose solutions to several challenges associated with the consistent formation and extended culture of cell spheroids generated from hPSCs and their differentiated progeny. Further, we provide examples to demonstrate how aggregation can be used as a tool to select specific subpopulations of cells to create homotypic spheroids, or as a means to introduce multiple cell types to create heterotypic tissue constructs. Finally, we demonstrate that the aggregation and rotary suspension method can be used to support culture and maintenance of hPSC-derived cell populations representing each of the three germ layers, underscoring the utility of this platform for culturing many different cell types.

Effects of in vitro endochondral priming and pre-vascularisation of human MSC cellular aggregates in vivo.

IntroductionDuring endochondral ossification, both the production of a cartilage template and the subsequent vascularisation of that template are essential precursors to bone tissue formation. Recent studies have found the application of both chondrogenic and vascular priming of mesenchymal stem cells (MSCs) enhanced the mineralisation potential of MSCs in vitro whilst also allowing for immature vessel formation. However, the in vivo viability, vascularisation and mineralisation potential of MSC aggregates that have been pre-conditioned in vitro by a combination of chondrogenic and vascular priming, has yet to be established. In this study, we test the hypothesis that a tissue regeneration approach that incorporates both chondrogenic priming of MSCs, to first form a cartilage template, and subsequent pre-vascularisation of the cartilage constructs, by co-culture with human umbilical vein endothelial cells (HUVECs) in vitro, will improve vessel infiltration and thus mineral formation once implanted in vivo.MethodsHuman MSCs were chondrogenically primed for 21 days, after which they were co-cultured with MSCs and HUVECs and cultured in endothelial growth medium for another 21 days. These aggregates were then implanted subcutaneously in nude rats for 4 weeks. We used a combination of bioluminescent imaging, microcomputed tomography, histology (Masson’s trichrome and Alizarin Red) and immunohistochemistry (CD31, CD146, and α-smooth actin) to assess the vascularisation and mineralisation potential of these MSC aggregates in vivo.ResultsPre-vascularised cartilaginous aggregates were found to have mature endogenous vessels (indicated by α-smooth muscle actin walls and erythrocytes) after 4 weeks subcutaneous implantation, and also viable human MSCs (detected by bioluminescent imaging) 21 days after subcutaneous implantation. In contrast, aggregates that were not pre-vascularised had no vessels within the aggregate interior and human MSCs did not remain viable beyond 14 days. Interestingly, the pre-vascularised cartilaginous aggregates were also the only group to have mineralised nodules within the cellular aggregates, whereas mineralisation occurred in the alginate surrounding the aggregates for all other groups.ConclusionsTaken together these results indicate that a combined chondrogenic priming and pre-vascularisation approach for in vitro culture of MSC aggregates shows enhanced vessel formation and increased mineralisation within the cellular aggregate when implanted subcutaneously in vivo.