Interplay of Physical, Psychological, and Social Frailty among Community-Dwelling Older Adults in Five European Countries: A Longitudinal Study.

Frailty is a dynamic condition encompassing physical, psychological, and social domains. While certain factors are associated with overall or specific frailty domains, research on the correlations between physical, psychological, and social frailty is lacking. This study aims to investigate the associations between physical, psychological, and social frailty in European older adults. The study involved 1781 older adults from the Urban Health Centres Europe project. Baseline and 1-year follow-up data were collected on physical, psychological, and social frailty, along with covariates. Linear regression analyzed unidirectional associations, while cross-lagged panel modeling assessed bi-directional associations. Participants' mean age was 79.57 years (SD = 5.54) and over half were female (61.0%). Physical and psychological frailty showed bi-directional association (effect of physical frailty at baseline on psychological frailty at follow-up: ß = 0.14, 95%CI 0.09, 0.19; reversed direction: ß = 0.05, 95%CI 0.01, 0.09). Higher physical frailty correlated with increased social frailty (ß = 0.05, 95%CI 0.01, 0.68), but no association was found between social and psychological frailty. This longitudinal study found a reciprocal relationship between physical and psychological frailty in older adults. A relatively higher level of physical frailty was associated with a higher level of social frailty. There was no association between social and psychological frailty. These findings underscore the multifaceted interplay between various domains of frailty. Public health professionals should recognize the implications of these interconnections while crafting personalized prevention and care strategies. Further research is needed to confirm these findings and investigate underlying mechanisms.

Socio-demographic characteristics associated with emotional and social loneliness among older adults.

BACKGROUND: International studies provide an overview of socio-demographic characteristics associated with loneliness among older adults, but few studies distinguished between emotional and social loneliness. This study examined socio-demographic characteristics associated with emotional and social loneliness. METHODS: Data of 2251 community-dwelling older adults, included at the baseline measure of the Urban Health Centers Europe (UHCE) project, were analysed. Loneliness was measured with the 6-item De Jong-Gierveld Loneliness Scale. Multivariable logistic regression models were used to evaluate associations between age, sex, living situation, educational level, migration background, and loneliness. RESULTS: The mean age of participants was 79.7 years (SD = 5.6 years); 60.4% women. Emotional and social loneliness were reported by 29.2 and 26.7% of the participants; 13.6% experienced emotional and social loneliness simultaneously. Older age (OR: 1.16, 95% CI: 1.06-1.28), living without a partner (2.16, 95% CI: 1.73-2.70), and having a low educational level (OR: 1.82, 95% CI: 1.21-2.73), were associated with increased emotional loneliness. Women living with a partner were more prone to emotional loneliness than men living with a partner (OR: 1.78, 95% CI: 1.31-2.40). Older age (OR: 1.11, 95% CI: 1.00-1.22) and having a low educational level (OR: 1.77, 95% CI: 1.14-2.74) were associated with increased social loneliness. Men living without a partner were more prone to social loneliness than men living with a partner (OR: 1.94, 95% CI: 1.35-2.78). CONCLUSIONS: Socio-demographic characteristics associated with emotional and social loneliness differed regarding sex and living situation. Researchers, policy makers, and healthcare professionals should be aware that emotional and social loneliness may affect older adults with different socio-demographic characteristics.

Albumin-based hydrogels for regenerative engineering and cell transplantation.

Albumin, the most abundant plasma protein in mammals, is a versatile and easily obtainable biomaterial. It is pH and temperature responsive, dissolvable in high concentrations and gels readily in defined conditions. This versatility, together with its inexpensiveness and biocompatibility, makes albumin an attractive biomaterial for biomedical research and therapeutics. So far, clinical research in albumin has centered mainly on its use as a carrier molecule or nanoparticle to improve drug pharmacokinetics and delivery to target sites. In contrast, research in albumin-based hydrogels is less established albeit growing in interest over recent years. In this minireview, we report current literature and critically discuss the synthesis, mechanical properties, biological effects and uses, biodegradability and cost of albumin hydrogels as a xeno-free, customizable, and transplantable construct for tissue engineering and regenerative medicine.

Association between physical, psychological and social frailty and health-related quality of life among older people.

BACKGROUND: Studies on the association between frailty and health-related quality of life (HRQoL) are scarce and show contradictory results. This study aimed to evaluate the association between physical, psychological and social frailty and HRQoL among community-dwelling older people. METHODS: A cross-sectional study was performed with baseline data collected in 2015 from the Urban Health Centers Europe (UHCE) project in five European countries, the United Kingdom, Greece, Croatia, The Netherlands and Spain. A total of 2325 participants were included in the baseline measurements of the Urban Health Centers Europe project; 2167 participants (mean age = 79.7; SD=5.6) were included in the analyses after excluding participants with missing data. The Tilburg Frailty Indicator measured overall frailty as well as physical, psychological and social frailty. The 12-Item Short-Form Health Survey was used to measured physical and mental HRQoL. RESULTS: Regarding physical HRQoL, a large difference (d=1.29) between physically and not physically frail participants was observed. Regarding mental HRQoL, a large difference (d=1.20) between psychologically and not psychologically frail participants was observed. In the full model with all three domains of frailty and the covariates to explain physical HRQoL, physical (P <0.001) and social frailty (P <0.001) remained significant. In the full model to explain mental HRQoL, all three domains of frailty remained significant (P <0.001). CONCLUSION: Physical frailty had the strongest association with physical HRQoL, and psychological frailty had the strongest association with mental HRQoL. The associations between social frailty and both physical and mental HRQoL remain significant when controlling for physical and psychological frailty.

A coordinated preventive care approach for healthy ageing in five European cities: A mixed methods study of process evaluation components.

AIMS: To evaluate specific process components of the Urban Health Centres Europe (UHCE) approach; a coordinated preventive care approach aimed at healthy ageing by decreasing falls, polypharmacy, loneliness and frailty among older persons in community settings of five cities in the United Kingdom, Greece, Croatia, the Netherlands and Spain. DESIGN: Mixed methods evaluation of specific process components of the UHCE approach: reach of the target population, dose of the intervention actually delivered and received by participants and satisfaction and experience of main stakeholders involved in the approach. METHODS: The UHCE approach intervention consisted of a preventive assessment, shared decision-making on a care plan and enrolment in one or more of four coordinated care-pathways that targeted falls, polypharmacy, loneliness and frailty. Quantitative data from a questionnaire and quantitative/qualitative data from logbooks were collected among older persons involved in the approach. Qualitative data from focus groups were collected among older persons, informal caregivers and professionals involved in the approach. Quantitative data were analysed by means of descriptive statistics and multilevel logistic regression models. Qualitative data were analysed through thematic analysis. RESULTS: Having limited function was associated with non-enrolment in falls and loneliness care-pathways (both p < .01). The mean rating of the approach was 8.3/10 (SD 1.9). Feeling supported by a care professional and meeting people were main benefits for older persons. Mistrust towards unfamiliar care providers, lack of confidence to engage in care activities and health constraints were main barriers towards engagement in care. CONCLUSIONS: Although the UHCE approach was received generally positively, health constraints and psychosocial barriers prevented older person's engagement in care. IMPACT: Coordinated preventive care approaches for older community-dwelling persons should address health constraints and psychosocial barriers that hinder older person's engagement in care. TRIAL REGISTRATION: ISRCTN registry number is ISRCTN52788952. Date of registration is 13/03/2017.

Advances in the generation of bioengineered bile ducts.

The generation of bioengineered biliary tissue could contribute to the management of some of the most impactful cholangiopathies associated with liver transplantation, such as biliary atresia or ischemic cholangiopathy. Recent advances in tissue engineering and in vitro cholangiocyte culture have made the achievement of this goal possible. Here we provide an overview of these developments and review the progress towards the generation and transplantation of bioengineered bile ducts. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni and Peter Jansen.

Densified collagen tubular grafts for human tissue replacement and disease modelling applications.

There is a significant need across multiple indications for an off-the-shelf bioengineered tubular graft which fulfils the mechanical and biological requirements for implantation and function but does not necessarily require cells for manufacture or deployment. Herein, we present a tissue-like tubular construct using a cell-free, materials-based method of manufacture, utilizing densified collagen hydrogel. Our tubular grafts are seamless, mechanically strong, customizable in terms of lumen diameter and wall thickness, and display a uniform fibril density across the wall thickness and along the tube length. While the method enables acellular grafts to be generated rapidly, inexpensively, and to a wide range of specifications, the cell-compatible densification process also enables a high density of cells to be incorporated uniformly into the walls of the tubes, which we show can be maintained under perfusion culture. Additionally, the method enables tubes consisting of distinct cell domains with cellular configurations at the boundaries which may be useful for modelling aortic disease. Further, we demonstrate additional steps which allow for luminal surface patterning. These results highlight the universality of this approach and its potential for developing the next generation of bioengineered grafts.

A vascularized tumoroid model for human glioblastoma angiogenesis.

Glioblastoma (GBM) angiogenesis is critical for tumor growth and recurrence, making it a compelling therapeutic target. Here, a disease-relevant, vascularized tumoroid in vitro model with stem-like features and stromal surrounds is reported. The model is used to recapitulate how individual components of the GBM's complex brain microenvironment such as hypoxia, vasculature-related stromal cells and growth factors support GBM angiogenesis. It is scalable, tractable, cost-effective and can be used with biologically-derived or biomimetic matrices. Patient-derived primary GBM cells are found to closely participate in blood vessel formation in contrast to a GBM cell line containing differentiated cells. Exogenous growth factors amplify this effect under normoxia but not at hypoxia suggesting that a significant amount of growth factors is already being produced under hypoxic conditions. Under hypoxia, primary GBM cells strongly co-localize with umbilical vein endothelial cells to form sprouting vascular networks, which has been reported to occur in vivo. These findings demonstrate that our 3D tumoroid in vitro model exhibits biomimetic attributes that may permit its use as a preclinical model in studying microenvironment cues of tumor angiogenesis.

3D Printable Vascular Networks Generated by Accelerated Constrained Constructive Optimization for Tissue Engineering.

One of the greatest challenges in fabricating artificial tissues and organs is the incorporation of vascular networks to support the biological requirements of the embedded cells, encouraging tissue formation and maturation. With the advent of 3D printing technology, significant progress has been made with respect to generating vascularized artificial tissues. Current algorithms to generate arterial/venous trees are computationally expensive and offer limited freedom to optimize the resulting structures. Furthermore, there is no method for algorithmic generation of vascular networks that can recapitulate the complexity of the native vasculature for more than two trees, and export directly to a 3D printing format. Here, we report such a method, using an accelerated constructive constrained optimization approach, by decomposing the process into construction, optimization, and collision resolution stages. The new approach reduces computation time to minutes at problem sizes where previous implementations have reported days. With the optimality criterion of maximizing the volume of useful tissue which could be grown around such a network, an approach of alternating stages of construction and batch optimization of all node positions is introduced and shown to yield consistently more optimal networks. The approach does not place a limit on the number of interpenetrating networks that can be constructed in a given space; indeed we demonstrate a biomimetic, liver-like tissue model. Methods to account for the limitations of 3D printing are provided, notably the minimum feature size and infill at sharp angles, through padding and angle reduction, respectively.

Spatial heterogeneity of cell-matrix adhesive forces predicts human glioblastoma migration.

BACKGROUND: Glioblastoma (GBM) is a highly aggressive incurable brain tumor. The main cause of mortality in GBM patients is the invasive rim of cells migrating away from the main tumor mass and invading healthy parts of the brain. Although the motion is driven by forces, our current understanding of the physical factors involved in glioma infiltration remains limited. This study aims to investigate the adhesion properties within and between patients' tumors on a cellular level and test whether these properties correlate with cell migration. METHODS: Six tissue samples were taken from spatially separated sections during 5-aminolevulinic acid (5-ALA) fluorescence-guided surgery. Navigated biopsy samples were collected from strongly fluorescent tumor cores, a weak fluorescent tumor rim, and nonfluorescent tumor margins. A microfluidics device was built to induce controlled shear forces to detach cells from monolayer cultures. Cells were cultured on low modulus polydimethylsiloxane representative of the stiffness of brain tissue. Cell migration and morphology were then obtained using time-lapse microscopy. RESULTS: GBM cell populations from different tumor fractions of the same patient exhibited different migratory and adhesive behaviors. These differences were associated with sampling location and amount of 5-ALA fluorescence. Cells derived from weak- and nonfluorescent tumor tissue were smaller, adhered less well, and migrated quicker than cells derived from strongly fluorescent tumor mass. CONCLUSIONS: GBM tumors are biomechanically heterogeneous. Selecting multiple populations and broad location sampling are therefore important to consider for drug testing.

Functionalisation of a heat-derived and bio-inert albumin hydrogel with extracellular matrix by air plasma treatment.

Albumin-based hydrogels are increasingly attractive in tissue engineering because they provide a xeno-free, biocompatible and potentially patient-specific platform for tissue engineering and drug delivery. The majority of research on albumin hydrogels has focused on bovine serum albumin (BSA), leaving human serum albumin (HSA) comparatively understudied. Different gelation methods are usually employed for HSA and BSA, and variations in the amino acid sequences of HSA and BSA exist; these account for differences in the hydrogel properties. Heat-induced gelation of aqueous HSA is the easiest method of synthesizing HSA hydrogels however hydrogel opacity and poor cell attachment limit their usefulness in downstream applications. Here, a solution to this problem is presented. Stable and translucent HSA hydrogels were created by controlled thermal gelation and the addition of sodium chloride. The resulting bio-inert hydrogel was then subjected to air plasma treatment which functionalised its surface, enabling the attachment of basement membrane matrix (Geltrex). In vitro survival and proliferation studies of foetal human osteoblasts subsequently demonstrated good biocompatibility of functionalised albumin hydrogels compared to untreated samples. Thus, air plasma treatment enables functionalisation of inert heat-derived HSA hydrogels with extracellular matrix proteins and these may be used as a xeno-free platform for biomedical research or cell therapy.

Reliability and Validity of the Tilburg Frailty Indicator in 5 European Countries.

OBJECTIVES: To assess the internal consistency, convergent and divergent validity, and concurrent validity of the Tilburg Frailty Indicator (TFI) within community-dwelling older people in Spain, Greece, Croatia, the Netherlands, and the United Kingdom. DESIGN: Cross-sectional study. SETTING: Primary care and community settings. PARTICIPANTS: In total, 2250 community-dwelling older people (60.3% women; mean age = 79.7 years; standard deviation = 5.7). METHODS: We assessed the reliability and validity of the full TFI as well as its physical, psychological, and social domains. Baseline data of the Urban Health Centers Europe project were used. The internal consistency was assessed with the Cronbach alpha. The convergent and divergent validity were assessed using Pearson correlation coefficients between the domains and alternative measures: the 12-item short-form, Groningen activity restriction scale, 5-item mental well-being scale of the 36-Item Short Form Survey, and the De Jong Gierveld loneliness scale. The concurrent validity was assessed by the area under the receiver operating characteristic curve with physically frail (Survey of Health, Ageing and Retirement in Europe-Frailty Instrument), loss of independence (Groningen activity restriction scale), limited function (Global Activity Limitation Index), poor mental health (5-item mental well-being scale of the 36-Item Short Form Survey), and feeling lonely (De Jong Gierveld loneliness scale) as criteria. RESULTS: The internal consistency of the full TFI was satisfactory with the Cronbach alpha ≥0.70 in the total population and in each country. The internal consistency of the psychological and social domains was not satisfactory. The convergent and divergent validity of the physical, psychological, and social domains was supported by all the alternative measures in the total population and in each country. The concurrent validity of the full TFI and the physical, psychological, and social domains was supported with most area under the receiver operating characteristic curve ≥0.70 in the total population and in each country. CONCLUSIONS AND IMPLICATIONS: The TFI is a reliable and valid instrument to assess frailty in community-dwelling older people in Spain, Greece, Croatia, the Netherlands, and the United Kingdom.

Feasibility of Using 3D Printed Polyvinyl Alcohol (PVA) for Creating Self-Healing Vascular Tunnels in Cement System.

Pursuing long-term self-healing infrastructures has gained popularity in the construction field. Vascular networks have the potential to achieve long-term self-healing in cementitious infrastructures. To avoid further monitoring of non-cementitious tubes, sacrificial material can be used as a way of creating hollow channels. In this research, we report a new method for fabrication of complex 3D internal hollow tunnels using 3D printing of polyvinyl alcohol (PVA). The behaviour of 3D printed PVA structures in cement pastes was investigated using computed-tomography (CT) combined with X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDX). Results showed that (i) 1300 min were needed to fully dissolve 1 g of a 3D printed PVA structure, and different pH solutions did not significantly change the PVA dissolving process compared with a neutral environment; (ii) a low water/cement ratio can minimize early stage cracking resulting from PVA expansion; (iii) and PVA-cement interaction products were mainly calcite and a Ca-polymer compound. In conclusion, controlling the PVA expansion by decreasing the water/cement (w/c) ratio provides a promising approach to achieve 3D hollow channels in cement and, therefore, makes it possible to create complex tunnels within self-healing cementitious materials.

Albumin-Enriched Fibrin Hydrogel Embedded in Active Ferromagnetic Networks Improves Osteoblast Differentiation and Vascular Self-Organisation.

Porous coatings on prosthetic implants encourage implant fixation. Enhanced fixation may be achieved using a magneto-active porous coating that can deform elastically in vivo on the application of an external magnetic field, straining in-growing bone. Such a coating, made of 444 ferritic stainless steel fibres, was previously characterised in terms of its mechanical and cellular responses. In this work, co-cultures of human osteoblasts and endothelial cells were seeded into a novel fibrin-based hydrogel embedded in a 444 ferritic stainless steel fibre network. Albumin was successfully incorporated into fibrin hydrogels improving the specific permeability and the diffusion of fluorescently tagged dextrans without affecting their Young's modulus. The beneficial effect of albumin was demonstrated by the upregulation of osteogenic and angiogenic gene expression. Furthermore, mineralisation, extracellular matrix production, and formation of vessel-like structures were enhanced in albumin-enriched fibrin hydrogels compared to fibrin hydrogels. Collectively, the results indicate that the albumin-enriched fibrin hydrogel is a promising bio-matrix for bone tissue engineering and orthopaedic applications.

Stimulation of Human Osteoblast Differentiation in Magneto-Mechanically Actuated Ferromagnetic Fiber Networks.

There is currently an interest in "active" implantable biomedical devices that include mechanical stimulation as an integral part of their design. This paper reports the experimental use of a porous scaffold made of interconnected networks of slender ferromagnetic fibers that can be actuated in vivo by an external magnetic field applying strains to in-growing cells. Such scaffolds have been previously characterized in terms of their mechanical and cellular responses. In this study, it is shown that the shape changes induced in the scaffolds can be used to promote osteogenesis in vitro. In particular, immunofluorescence, gene and protein analyses reveal that the actuated networks exhibit higher mineralization and extracellular matrix production, and express higher levels of osteocalcin, alkaline phosphatase, collagen type 1α1, runt-related transcription factor 2 and bone morphogenetic protein 2 than the static controls at the 3-week time point. The results suggest that the cells filling the inter-fiber spaces are able to sense and react to the magneto-mechanically induced strains facilitating osteogenic differentiation and maturation. This work provides evidence in support of using this approach to stimulate bone ingrowth around a device implanted in bone and can pave the way for further applications in bone tissue engineering.

Isolation and propagation of primary human cholangiocyte organoids for the generation of bioengineered biliary tissue.

Pediatric liver transplantation is often required as a consequence of biliary disorders because of the lack of alternative treatments for repairing or replacing damaged bile ducts. To address the lack of availability of pediatric livers suitable for transplantation, we developed a protocol for generating bioengineered biliary tissue suitable for biliary reconstruction. Our platform allows the derivation of cholangiocyte organoids (COs) expressing key biliary markers and retaining functions of primary extra- or intrahepatic duct cholangiocytes within 2 weeks of isolation. COs are subsequently seeded on polyglycolic acid (PGA) scaffolds or densified collagen constructs for 4 weeks to generate bioengineered tissue retaining biliary characteristics. Expertise in organoid culture and tissue engineering is desirable for optimal results. COs correspond to mature functional cholangiocytes, differentiating our method from alternative organoid systems currently available that propagate adult stem cells. Consequently, COs provide a unique platform for studies in biliary physiology and pathophysiology, and the resulting bioengineered tissue has broad applications for regenerative medicine and cholangiopathies.

The effectiveness of a coordinated preventive care approach for healthy ageing (UHCE) among older persons in five European cities: A pre-post controlled trial.

BACKGROUND: Older persons often have multiple health and social problems and need a variety of health services. A coordinated preventive approach that integrates the provision of health and social care services could promote healthy ageing. Such an approach can be organised differently, depending on the availability and organizational structures in the local context. Therefore, it is important to evaluate the effectiveness of a coordinated preventive care approach in various European settings. OBJECTIVES: This study explored the effects of a coordinated preventive health and social care approach on the lifestyle, health and quality of life of community-dwelling older persons in five European cities. DESIGN: International multi-center pre-post controlled trial. SETTING: Community settings in cities in the United Kingdom, Greece, Croatia, the Netherlands and Spain. PARTICIPANTS: 1844 community-dwelling older persons (mean age = 79.5; SD = 5.6). METHODS: The Urban Health Centres Europe (UHCE) approach consisted of a preventive multidimensional health assessment and, if a person was at-risk, coordinated care-pathways targeted at fall risk, appropriate medication use, loneliness and frailty. Intervention and control sites were chosen based on their location in distinct neighbourhoods in the participating cities. Persons in the catchment area of the intervention sites 'the intervention group' received the UHCE approach and persons in catchment areas of the control sites 'the control group' received care as usual. A questionnaire and two measurements were taken at baseline and at one-year follow-up to assess healthy lifestyle, fall risk, appropriate medication use, loneliness level, frailty, level of independence, health-related quality of life and care use. To evaluate differences in outcomes between intervention group and control group for the total study population, for those who received follow-up care-pathways and for each city separately (multilevel) logistic and linear regression analyses were used. RESULTS: Persons in the intervention group had less recurrent falls (OR = 0.65, 95% CI = 0.48; 0.88) and lower frailty (B=-0.43, 95% CI= -0.65 to -0.22) at follow-up compared with persons in the control group. Physical health-related quality of life and mental well-being was better (B = 0.95; 95% CI = 0.14-1.76; and B = 1.50; 95% CI = 0.15-2.84 respectively). The effects of the UHCE approach were stronger in the subgroup of persons (53.6%) enrolled in care-pathways. CONCLUSIONS: Our study found promising but minor effects for the use of a coordinated preventive health and social care approach for the promotion of healthy ageing of older persons. Future studies should further evaluate effects of coordinated preventive health and social care aimed at healthy ageing. TRIAL REGISTRATION: ISRCTN registry number is ISRCTN52788952. Date of registration is 13/03/2017.

Effect of Rotation on Scaffold Motion and Cell Growth in Rotating Bioreactors.

Efficient use of different bioreactor designs to improve cell growth in three-dimensional scaffolds requires an understanding of their mechanism of action. To address this for rotating wall vessel bioreactors, fluid and scaffold motion were investigated experimentally at different rotation speeds and vessel fill volumes. Low cost bioreactors with single and dual axis rotation were developed to investigate the effect of these systems on human osteoblast proliferation in free floating and constrained collagen-glycosaminoglycan porous scaffolds. A range of scaffold motions (free fall, periodic oscillation, and orbital motion) were observed at the rotation speeds and vessel fluid/air ratios used, with 85% fluid fill and an outer vessel wall velocity of ∼14 mm s-1 producing a scaffold in a free fall state. The cell proliferation results showed that after 14 and 21 days of culture, this combination of fluid fill and speed of rotation produced significantly greater cell numbers in the scaffolds than when lower or higher rotation speeds (p < 0.002) or when the chamber was 60% or 100% full (p < 0.01). The fluid flow and scaffold motion experiments show that biaxial rotation would not improve the mass transfer of medium into the scaffold as the second axis of rotation can only transition the scaffold toward oscillatory or orbital motion and, hence, reduce mass transport to the scaffold. The cell culture results confirmed that there was no benefit to the second axis of rotation with no significant difference in cell proliferation either when the scaffolds were free floating or constrained (p > 0.05).

Reconstruction of the mouse extrahepatic biliary tree using primary human extrahepatic cholangiocyte organoids.

The treatment of common bile duct (CBD) disorders, such as biliary atresia or ischemic strictures, is restricted by the lack of biliary tissue from healthy donors suitable for surgical reconstruction. Here we report a new method for the isolation and propagation of human cholangiocytes from the extrahepatic biliary tree in the form of extrahepatic cholangiocyte organoids (ECOs) for regenerative medicine applications. The resulting ECOs closely resemble primary cholangiocytes in terms of their transcriptomic profile and functional properties. We explore the regenerative potential of these organoids in vivo and demonstrate that ECOs self-organize into bile duct-like tubes expressing biliary markers following transplantation under the kidney capsule of immunocompromised mice. In addition, when seeded on biodegradable scaffolds, ECOs form tissue-like structures retaining biliary characteristics. The resulting bioengineered tissue can reconstruct the gallbladder wall and repair the biliary epithelium following transplantation into a mouse model of injury. Furthermore, bioengineered artificial ducts can replace the native CBD, with no evidence of cholestasis or occlusion of the lumen. In conclusion, ECOs can successfully reconstruct the biliary tree, providing proof of principle for organ regeneration using human primary cholangiocytes expanded in vitro.

Multi-casting approach for vascular networks in cellularized hydrogels.

Vascularization is essential for living tissue and remains a major challenge in the field of tissue engineering. A lack of a perfusable channel network within a large and densely populated tissue engineered construct leads to necrotic core formation, preventing fabrication of functional tissues and organs. We report a new method for producing a hierarchical, three-dimensional (3D) and perfusable vasculature in a large, cellularized fibrin hydrogel. Bifurcating channels, varying in size from 1 mm to 200-250 µm, are formed using a novel process in which we convert a 3D printed thermoplastic material into a gelatin network template, by way of an intermediate alginate hydrogel. This enables a CAD-based model design, which is highly customizable, reproducible, and which can yield highly complex architectures, to be made into a removable material, which can be used in cellular environments. Our approach yields constructs with a uniform and high density of cells in the bulk, made from bioactive collagen and fibrin hydrogels. Using standard cell staining and immuno-histochemistry techniques, we showed good cell seeding and the presence of tight junctions between channel endothelial cells, and high cell viability and cell spreading in the bulk hydrogel.