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As a naturally occurring mineral component of bone, hydroxyapatite (HA) is a preferred bone-repair material in clinical medicine. This adaptable biomaterial is developed from synthetic or biological sources. The goal of this study was to investigate the physicochemical and biological properties of scaffolds made from diverse hydroxyapatite sources. We prepared hydroxyapatite powders either from naturally occurring sources, using decellularized bone extracellular matrix (DBECM) and deproteinized bovine bone (DBB), or in the laboratory using the co-precipitation method. Although XRD analysis confirmed the pure phase of HA in all three powders, XRF data found some other trace elements in bone-derived biomaterials, such as magnesium and strontium. Further, FTIR spectra showed DBECM-associated macromolecule peaks. In the second phase of this study, the particles were mixed with sodium alginate to produce bioink for 3D printing via extrusion. SEM photographs of the printed scaffolds showed a grid-like porous structure with large, interconnected pores. Although all of the scaffolds retained their structural integrity after 28 days submerged in the culture medium, DBECM-based scaffolds degraded the most. The test of Young's modulus and compressive strength of scaffolds revealed that all scaffolds are strong enough to be employed in non-weight-bearing applications. The biological characteristics of the scaffolds were then evaluated via cytotoxicity analysis, SEM examination of cell attachment, MTT assay, ALP activity assessment, immunofluorescence staining, and Alizarin red staining. The results indicated that all three scaffolds provided a surface that promoted adhesion and proliferation of rat bone marrow mesenchymal stem cells (rMSCs), as well as stimulated the production of mineralized extracellular matrices. Additionally, our findings showed that scaffolds made from DBECM powders offer the best environment for cell activity. This is most likely due to the presence of trace elements and protein macromolecules in DBECM powders that are not found in DBB and synthetic HA. In conclusion, our comparative study revealed that while all three scaffolds are suitable for bone tissue engineering, DBECM-based scaffolds outperform DBB and synthetic HA. [ABSTRACT FROM AUTHOR]

This correction notice addresses errors in a scientific paper titled "A Cell-Free SDKP-Conjugated Self-Assembling Peptide Hydrogel Sufficient for Improvement of Myocardial Infarction." The authors discovered that some representative images in Figures 4 and 5 overlapped with images from another published paper. This occurred because the experiments were performed simultaneously. The authors apologize for any inconvenience caused and state that the scientific conclusions were unaffected. The corrected version of the paper will be updated on the article webpage. Additionally, a correction was made to the peptide sequence in the Materials and Methods section due to intellectual property issues. The paper includes graphs showing the effects of the hydrogel on scar size, angiogenesis, and inflammation. [Extracted from the article]

Early detection of cis phosphorylated tau (cis P-tau) may help as an effective treatment to control the progression of Alzheimer's disease (AD). Recently, we introduced for the first time a monoclonal antibody (mAb) with high affinity against cis P-tau. In this study, the cis P-tau mAb was utilized to develop a label-free immunosensor. The antibody was immobilized onto a gold electrode and the electrochemical responses to the analyte were acquired by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The immunosensor was capable of selective detection of cis P-tau among non-specific targets like trans P-tau and major plasma proteins. A wide concentration range (10 × 10−14 M–3.0 × 10−9 M) of cis P-tau was measured in PBS and human serum matrices with a limit of detection of 0.02 and 0.05 pM, respectively. Clinical applicability of the immunosensor was suggested by its long-term storage stability and successful detection of cis P-tau in real samples of cerebrospinal fluid (CSF) and blood serum collected from human patients at different stages of AD. These results suggest that this simple immunosensor may find great application in clinical settings for early detection of AD which is an unmet urgent need in today's healthcare services. [ABSTRACT FROM AUTHOR]

A dual cross-linking strategy was developed to answer the urgent need for fatigue-resistant, cytocompatible, and in situ forming tough hydrogels. Clickable, yet calcium-binding derivatives of alginate were synthesized by partial substitution of its carboxyl functionalities with furan, which could come into Diels-Alder click reaction with maleimide end groups of a four arm poly(ethylene glycol) cross-linker. Tuning the cooperative viscoelastic action of transient ionic and permanent click cross-links within the single network of alginate provided a soft tough hydrogel with a set of interesting features: (i) immediate self-recovery under cyclic loading, (ii) highly efficient and autonomous self-healing upon fracture, (iii) in situ forming ability for molding and minimally invasive injection, (iv) capability for viable cell encapsulation, and (v) reactivity for on-demand biomolecule conjugation. The facile strategy is applicable to a wide range of natural and synthetic polymers by introducing the calcium binding and click reacting functional groups and can broaden the use of tough hydrogels in load-bearing, cell-laden applications such as soft tissue engineering and bioactuators. [ABSTRACT FROM AUTHOR]

Human embryonic stem cell (hESC)-derived endodermal cells are of interest for the development of cellular therapies to treat disorders such as liver failure. The soluble form of activin A (Act) has been widely used as an in vitro inducer of definitive endoderm (DE). In this study, we have developed a nanofibrous poly (ɛ-caprolactone) substrate, biofunctionalized with Act, for directed differentiation of hESCs into DE. Bioconjugation of Act on nanofibrous meshes was confirmed by enzyme-linked immunosorbent assay (ELISA) and immunostaining. In order to investigate the bioactivity of immobilized Act (iAct), hESCs were cultivated on the Act-conjugated nanofibers for five days. The nanofibers with covalent iAct significantly increased expression levels of the endodermal markers SOX17, FOXA2, and CXCR4, compared with physically adsorbed Act (aAct) or without Act (noAct). In addition, iAct retained its bioactivity after storage for five days in the absence of cell seeding. The capability of cultivated cells to generate the DE-derived lineage was evaluated through further differentiation of seeded cells into hepatocyte-like cells (HLCs). Interestingly, the iAct sample showed a higher level of hepatic markers compared to the aAct sample. We also demonstrated that iAct in the presence of soluble Act (sAct) could improve the conventional protocol to generate HLCs from hESCs. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2861-2872, 2016. [ABSTRACT FROM AUTHOR]

Derivation of definitive endoderm (DE) from human embryonic stem cells (hESCs) can address the needs of regenerative medicine for endoderm-derived organs such as the pancreas and liver. Fibrous substrates which topographically recapitulate native extracellular matrix have been known to promote the stem cell differentiation. However, the optimal fiber diameter remains to be determined for the desired differentiation. Here, we have developed a simple method to precisely fabricate electrospun poly(ε-caprolactone) fibers with four distinct average diameters at nano- and microscale levels (200, 500, 800, and 1300 nm). Human ESCs were cultured as clumps or single cells and induced into DE differentiation to determine the optimal topography leading to the promoted differentiation compared with planar culture plates. Gene expression analysis of the DE-induced cells showed significant upregulation of DE-specific genes exclusively on the 200-nm fibers. By Western blot analysis, significant expression of DE-specific proteins was found when hESCs were cultured on the 200 nm substrate as single cells rather than clumps, probably due to more efficient cell-matrix interaction realized by morphological observations of the cell colonies. The results indicated that nanofibrillar substrates, only at ultrathin fiber diameters, provided a better environment for DE differentiation of hESC, which holds great promise in prospective tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3539-3553, 2015. [ABSTRACT FROM AUTHOR]

Liver organoids (LOs) are receiving considerable attention for their potential use in drug screening, disease modeling, and transplantable constructs. Hepatocytes, as the key component of LOs, are isolated from the liver or differentiated from pluripotent stem cells (PSCs). PSC-derived hepatocytes are preferable because of their availability and scalability. However, efficient maturation of the PSC-derived hepatocytes towards functional units in LOs remains a challenging subject. The incorporation of cell-sized microparticles (MPs) derived from liver extracellular matrix (ECM), could provide an enriched tissue-specific microenvironment for further maturation of hepatocytes inside the LOs. In the present study, the MPs were fabricated by chemical cross-linking of a water-in-oil dispersion of digested decellularized sheep liver. These MPs were mixed with human PSC-derived hepatic endoderm, human umbilical vein endothelial cells, and mesenchymal stromal cells to produce homogenous bioengineered LOs (BLOs). This approach led to the improvement of hepatocyte-like cells in terms of gene expression and function, CYP activities, albumin secretion, and metabolism of xenobiotics. The intraperitoneal transplantation of BLOs in an acute liver injury mouse model led to an enhancement in survival rate. Furthermore, efficient hepatic maturation was demonstrated after ex ovo transplantation. In conclusion, the incorporation of cell-sized tissue-specific MPs in BLOs improved the maturation of human PSC-derived hepatocyte-like cells compared to LOs. This approach provides a versatile strategy to produce functional organoids from different tissues and offers a novel tool for biomedical applications. [ABSTRACT FROM AUTHOR]

Biomaterials in conjunction with stem cell therapy have recently attracted attention as a new therapeutic approach for myocardial infarction (MI), with the aim to solve the delivery challenges that exist with transplanted cells. Self-assembling peptide (SAP) hydrogels comprise a promising class of synthetic biomaterials with cardiac-compatible properties such as mild gelation, injectability, rehealing ability, and potential for sequence modification. Herein, we developed an SAP hydrogel composed of a self-assembling gel-forming core sequence (RADA) modified with SDKP motif with pro-angiogenic and anti-fibrotic activity to be used as a cardioprotective scaffold. The RADA-SDKP hydrogel was intramyocardially injected into the infarct border zone of a rat model of MI induced by left anterior descending artery (LAD) ligation as a cell-free or a cell-delivering scaffold for bone marrow mesenchymal stem cells (BM-MSCs). The left ventricular ejection fraction (LVEF) was markedly improved after transplantation of either free hydrogel or cell-laden hydrogel. This cardiac functional repair coincided very well with substantially lower fibrotic tissue formation, expanded microvasculature, and lower inflammatory response in the infarct area. Interestingly, BM-MSCs alone or in combination with hydrogel could not surpass the cardiac repair effects of the SDKP-modified SAP hydrogel. Taken together, we suggest that the RADA-SDKP hydrogel can be a promising cell-free construct that has the capability for functional restoration in the instances of acute myocardial infarction (AMI) that might minimize the safety concerns of cardiac cell therapy and facilitate clinical extrapolation. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Microneedle patches have been widely used as transdermal transport systems because of their painless and easy application. Marked rigidity, strength, biocompatibility, and physiological stability are unique features of microneedles fabricated from ceramic materials to be used as microneedle patches. However, the conventional ceramic microneedles are typically dense structures with limited free space for biomolecule loading. A facile method is required for fabrication of biocompatible ceramic microneedles with interconnected porosity. Herein, the simple method of centrifugal casting was developed for fabrication of microporous microneedles from alumina suspensions. The slurry or resin-based alumina suspensions were casted into micromolds under centrifugal force, followed by sintering at high temperatures. The effects of particle size, solvent type, binder amount, resin content and sintering temperature on the microstructure and mechanical properties of microneedles were investigated. By optimizing the process parameters, highly porous (up to 60%) microneedles with interconnected micropores (of diameter ∼1–1.5 μm) were produced. The microporous microneedles were biocompatible and mechanically strong for skin penetration. The potential use of the microneedles for transdermal transportation of biomolecules was shown by fast and accurate extraction of glucose from a skin model and efficient loading and fast release of insulin under physiological conditions. The results suggested that the microporous alumina microneedles may serve as molecular transport systems in transdermal biosensing and drug delivery. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) are considered primary candidates for treating complex bone defects in cell-based therapy and tissue engineering. Compared with monolayer cultures, spheroid cultures of MSCs (mesenspheres) are favorable due to their increased potential for differentiation, extracellular matrix (ECM) synthesis, paracrine activity, and in vivo engraftment. Here, we present a strategy for the incorporation of microparticles for the fabrication of osteogenic micro-tissues from mesenspheres in a cost-effective and scalable manner. A facile method was developed to synthesize mineral microparticles with cell-sized spherical shape, biphasic calcium phosphate composition (hydroxyapatite and β-tricalcium phosphate), and a microporous structure. Calcium phosphate microparticles (CMPs) were incorporated within the mesenspheres through mixing with the single cells during cell aggregation. Interestingly, the osteogenic genes were upregulated significantly (collagen type 1 (Col 1) 30-fold, osteopontin (OPN) 10-fold, and osteocalcin (OCN) 3-fold) after 14 days of culture with the incorporated CMPs, while no significant upregulation was observed with the incorporation of gelatin microparticles. The porous structure of the CMPs was exploited for loading and sustained release of an angiogenic small molecule. Dimethyloxaloylglycine (DMOG) was loaded efficiently onto the CMPs (loading efficiency: 65.32 ± 6%) and showed a sustained release profile over 12 days. Upon incorporation of the DMOG-loaded CMPs (DCMPs) within the mesenspheres, a similar osteogenic differentiation and an upregulation in angiogenic genes (VEGF 5-fold and kinase insert domain (KDR) 2-fold) were observed after 14 days of culture. These trends were also observed in immunostaining analysis. To evaluate scalable production of the osteogenic micro-tissues, the incorporation of microparticles was performed during cell aggregation in a spinner flask. The DCMPs were efficiently incorporated and directed the mesenspheres toward osteogenesis and angiogenesis. Finally, the DCMP mesenspheres were loaded within a three-dimensional printed cell trapper and transplanted into a critical-sized defect in a rat model. Computed tomography and histological analysis showed significant bone formation with blood vessel reconstruction after 8 weeks in this group. Taken together, we provide a scalable and cost-effective approach for fabrication of osteogenic micro-tissues, as building blocks of macro-tissues, that can address the large amounts of cells required for cell-based therapies.