Macro-encapsulation of mesenchymal stem cells in acute and chronic liver injury animal models.

BACKGROUND AND AIM: Stem cell treatments using scaffolds for liver disease have been well studied. However, macro-encapsulation of mesenchymal stem cells (MSCs) to minimize or inhibit stem cell homing has not been evaluated. Here, we conducted a proof-of-concept study using MSCs macro-encapsulated in poly lactic-co-glycolic acid in liver disease models. METHODS: Poly lactic-co-glycolic acid semipermeable membranes (surface pore size up to 40 µm) were used as the macro-encapsulation system. Macro-encapsulated pouches were loaded with MSCs and sealed. Each pouch was implanted in the subcutaneous region of the dorsum or interlobular space of the liver. Acute liver injury was induced using thioacetamide intraperitoneal injection thrice a week. For the chronic liver fibrosis model, thioacetamide dose was gradually increased, starting from 100 to 400 mg/kg over 16 weeks (thrice a week). RESULTS: In the acute liver injury model, the treated groups showed decreased liver inflammation and necrosis compared with the control. Hepatic fibrosis decreased in the treated group in the chronic liver fibrosis model compared with that in the control group. Encapsulated MSCs exhibited changed cell morphology and characteristics after implantation, showing increased periodic acid-Schiff staining and CYP2E1 expression. Migration and homing of MSCs into the liver was not observed. Under hypoxic conditions, macro-encapsulated MSCs secreted more growth hormones, including vascular endothelial growth factor, platelet-derived growth factor, angiopoietin-2, and placental growth factor, than monolayered MSCs in vitro. CONCLUSIONS: Macro-encapsulated MSCs attenuate hepatic inflammation and fibrosis by upregulating hypoxia-induced growth hormone secretion in liver disease models.

Effect of an oxygen-generating scaffold on the viability and insulin secretion function of porcine neonatal pancreatic cell clusters.

BACKGROUND: Islet encapsulation techniques have shown limited success in maintaining islet survival and function because encapsulation decreases oxygen supply. In this study, an oxygen-generating scaffold was fabricated to prevent hypoxic cell damage and improve the viability and insulin secretion of islets. METHODS: We fabricated an oxygen-generating scaffold by mixing calcium peroxide (CaO2 ) with polydimethylsiloxane (PDMS). We evaluated the effects of the oxygen-generating PDMS + CaO2 scaffold on viability, caspase-3 and caspase-7 activity, oxygen consumption rate (OCR), glucose-stimulated insulin secretion (GSIS), hypoxic cell marker expression, and reactive oxygen species (ROS) levels in porcine neonatal pancreatic cell clusters (NPCCs). We also fabricated a microfluidic device that allowed measuring the effects of the oxygen-generating scaffold on viability. RESULTS: Oxygen generation by the PDMS + CaO2 scaffold was sustained for more than 24 hours in vitro. NPCCs encapsulated in PDMS + CaO2 showed higher viability than NPCCs in PDMS scaffolds and control NPCCs grown without a scaffold. PDMS + CaO2 -encapsulated NPCCs showed lower caspase-3 and caspase-7 activity, hypoxic cell expression, and ROS levels, and higher OCR and GSIS than those in PDMS or control cells. Using the microfluidic device, we observed that the viability of PDMS + CaO2 -encapsulated NPCCs was higher than that of PDMS-encapsulated NPCCs. CONCLUSIONS: NPCCs in PDMS + CaO2 scaffolds show higher viability and insulin secretion than do NPCCs in PDMS scaffolds and control cells. Therefore, this oxygen-generating scaffold has potential for application in future islet transplantation studies.

Waffle-inspired hydrogel-based macrodevice for spatially controlled distribution of encapsulated therapeutic microtissues and pro-angiogenic endothelial cells.

Macro-encapsulation systems for delivery of cellular therapeutics in diabetes treatment offer major advantages such as device retrievability and high cell packing density. However, microtissue aggregation and absence of vasculature have been implicated in the inadequate transfer of nutrients and oxygen to the transplanted cellular grafts. Herein, we develop a hydrogel-based macrodevice to encapsulate therapeutic microtissues positioned in homogeneous spatial distribution to mitigate their aggregation while concurrently supporting an organized intra-device network of vascular-inductive cells. Termed Waffle-inspired Interlocking Macro-encapsulation (WIM) device, this platform comprises two modules with complementary topography features that fit together in a lock-and-key configuration. The waffle-inspired grid-like micropattern of the "lock" component effectively entraps insulin-secreting microtissues in controlled locations while the interlocking design places them in a co-planar spatial arrangement with close proximity to vascular-inductive cells. The WIM device co-laden with INS-1E microtissues and human umbilical vascular endothelial cells (HUVECs) maintains desirable cellular viability in vitro with the encapsulated microtissues retaining their glucose-responsive insulin secretion while embedded HUVECs express pro-angiogenic markers. Furthermore, a subcutaneously implanted alginate-coated WIM device encapsulating primary rat islets achieves blood glucose control for 2 weeks in chemically induced diabetic mice. Overall, this macrodevice design lays foundation for a cell delivery platform, which has the potential to facilitate nutrients and oxygen transport to therapeutic grafts and thereby might lead to improved disease management outcome.

Parathyroid Allotransplantation: A Systematic Review.

Background: To date, there is no satisfactory treatment for patients with calcium and vitamin D supplementation refractive hypoparathyroidism. Parathyroid allotransplantation by design is a one-time cure through its restoration of the parathyroid function and, therefore, could be the solution. A systematic literature review is conducted in the present paper, with the aim of outlining the possibilities of parathyroid allotransplantation and to calculate its efficacy. Additionally, various transplantation characteristics are linked to success. Methods: This review is carried out according to the PRISMA statement and checklist. Relevant articles were searched for in medical databases with the most recent literature search performed on 9 December 2021. Results: In total, 24 articles involving 22 unique patient cohorts were identified with 203 transplantations performed on 148 patients. Numerous types of (exploratory) interventions were carried out with virtually no protocols that were alike: there was the use of (non-) cryopreserved parathyroid tissue combined with direct transplantation or pretreatment using in vitro techniques, such as culturing cells and macro-/microencapsulation. The variability increased further when considering immunosuppression, graft histology, and donor-recipient compatibility, but this was found to be reported in its entirety by exception. As a result of the large heterogeneity among studies, we constructed our own criterium for transplantation success. With only the studies eligible for our assessment, the pooled success rate for parathyroid allotransplantation emerged to be 46% (13/28 transplantations) with a median follow-up duration of 12 months (Q1-Q3: 8-24 months). Conclusions: Manifold possibilities have been explored around parathyroid allotransplantation but are presented as a double-edged sword due to high clinical diverseness, low expertise in carrying out the procedure, and unsatisfactory study quality. Transplantations carried out with permanent immunosuppression seem to be the most promising, but, in its current state, little could be said about the treatment efficacy with a high quality of evidence. Of foremost importance in pursuing the answer whether parathyroid allotransplantation is a suitable treatment for hypoparathyroidism, a standardized definition of transplantation success must be established with a high-quality trial.

A tailored permeable reactive bio-barrier for in situ groundwater remediation: removal of 3-chlorophenol as a case study.

The present study explored bacterial aerobic biodegradation of reduced carbon-contaminants (RCC) in a pilot system mimicking remediation of a saturated aquifer in a permeable reactive biobarrier (PRBB). Bioaugmentation was performed with a pure culture of Pseudomonas putida macro-encapsulated in a cellulose-acetate porous envelope and integrated transversely to the flow trajectory of the fluid in the biobarrier and compared with controls without capsules. The macro-encapsulation technique applied allowed the incorporation of a built-in nutrient core for the slow release of macronutrients, i.e. N, P, instead of exogenous nutrients supply. 3-Chlorophenol (3CP) at a concentration range of 350-500 mg/L was chosen as an RCC model compound. The findings indicate efficient 3CP biodegradation during the PRBB operation with a similar degree of transformation (76 ± 2% and 72 ± 2%) and mineralization (55 ± 4% vs. 49 ± 3%) for exogenous and built-in nutrients supply, respectively. The extent of dechlorination in both cases (54 ± 10% vs. 40 ± 2%, respectively) followed mineralization rather than transformation, suggesting that Cl- release took place in late transformation stages. Negligible decontamination was observed in the control system without bioaugmentation. Concluding, tailored PRBB with macro-capsules incorporating a built-in nutrient core to support bacterial growth presents a significant environmental advantage controlling excess nutrients release required in bioremediation of oligotrophic systems.

Study on the Frost Resistance of Concrete Modified with Steel Balls Containing Phase Change Material (PCM).

In order to investigate the effect of phase change materials on the frost resistance of concrete in cold regions, hollow steel balls were used in this paper for the macroscopic encapsulation of the phase change material to replace some of the coarse aggregates in the preparation of phase change concrete. On the premise of ensuring reasonable mechanical properties, concrete mixed with different contents and different surface treatments of grouting steel balls were tested for the compressive strength and splitting tensile strength to determine the optimum content of phase change steel balls and investigate the frost resistance of phase change concrete. At the same time, industrial CT was used to explore the internal pore evolution pattern of concrete during the freeze-thaw period. The test results show that the optimum content of steel balls is 75%; during the freeze-thaw process, the mass loss, relative dynamic elastic modulus loss, and strength loss of phase change concrete are all lower than those of ordinary concrete, and the increase in porosity of phase change concrete is also significantly lower than that of ordinary concrete; the addition of phase change materials can optimise the distribution of the internal pore in concrete, improve its internal pore structure, and enhance its frost resistance.

Mechanical and Thermal Performance of Macro-Encapsulated Phase Change Materials for Pavement Application.

Macro-encapsulated phase change material (PCM) lightweight aggregates (ME-LWA) were produced and evaluated for their mechanical and thermal properties in road engineering applications. The ME-LWAs were first characterised in terms of their physical and geometrical properties. Then, the ME-LWAs were investigated in detail by applying the European Standards of testing for the Bulk Crushing Test and the Polished Stone Value (PSV) coefficient as well as Micro-Deval and laboratory profilometry. In addition, the thermal performance for possible construction of smart pavements with the inclusion of ME-LWAs for anti-ice purposes was determined. The crushing resistance of the ME-LWAs was improved, while their resistance to polishing was reduced. Thermal analysis of the encapsulated PCM determined it to possess excellent thermal stability and a heat storage capacity of 30.43 J/g. Based on the research findings, the inclusion of ME-LWAs in surface pavement layers could be considered a viable solution for the control of surface temperatures in cold climates. Road safety and maintenance could benefit in terms of reduced ice periods and reduced treatments with salts and other anti-ice solutions.

Preparation and Characterization of Expanded Clay-Paraffin Wax-Geo-Polymer Composite Material.

Paraffin-based phase change material (PCM) is impregnated into the pores of lightweight expanded clay aggregate (LECA) through vacuum impregnation to develop PCM containing macro-capsules of LECA. Three different grades of LECA varying in size and morphology are investigated to host the PCM to determine the impregnation effectiveness, viability for coating, and its stability. The produced LECA-PCM is coated with geopolymer paste (GP) to provide leak proofing during the phase change. The PCM is thermophysically characterized by employing differential scanning calorimetry (DSC) and the temperature history method (THM) to determine the phase transition and the latent heat. The stability of the macro-capsules is determined by weight loss through rapid thermal cycling (RTC) at elevated temperatures. Leakage of the PCM is tested using the diffusion-oozing circle test (DOCT). The results show that the GP coated LECA-PCM macro-capsules achieved 87 wt % impregnation efficiencies and no noticeable loss of PCM, which indicates leak proofing of the developed capsules up to 1000 RTC.

Macro-Encapsulation of Inorganic Phase-Change Materials (PCM) in Metal Capsules.

The design of phase-change material (PCM)-based thermal energy storage (TES) systems is challenging since a lot of PCMs have low thermal conductivities and a considerable volume change during phase-change. The low thermal conductivity restricts energy transport due to the increasing thermal resistance of the progressing phase boundary and hence large heat transfer areas or temperature differences are required to achieve sufficient storage power. An additional volume has to be considered in the storage system to compensate for volume change. Macro-encapsulation of the PCM is one method to overcome these drawbacks. When designed as stiff containers with an air cushion, the macro-capsules compensate for volume change of the PCM which facilitates the design of PCM storage systems. The capsule walls provide a large surface for heat transfer and the thermal resistance is reduced due to the limited thickness of the capsules. Although the principles and advantages of macro-encapsulation have been well known for many years, no detailed analysis of the whole encapsulation process has been published yet. Therefore, this research proposes a detailed development strategy for the whole encapsulation process. Various possibilities for corrosion protection, fill and seal strategies and capsule geometries are studied. The proposed workflow is applied for the encapsulation of the salt hydrate magnesiumchloride hexahydrate (MCHH, MgCl 2 · 6 H 2 O) within metal capsules but can also be assigned to other material combinations.

Macro-Encapsulated PCM Cylinder Module Based on Paraffin and Float Stones.

Organic phase change material (PCM) with macro-encapsulation is attractive in energy storage applications as it has relatively low cost. This study focuses on using PET plastic pipes to encapsulate paraffin and using low-cost float stones to increase the thermal conductivity of PCM modules as they have a special structure of high porosity. Float stones were immersed in the liquid PCM and an ultrasonic welding method used to prevent leakage of the PET plastic pipes. Scanning electron microscopy (SEM) was used to discover the appearance of the composite PCM. The thermal performance of the PCM cylinder module was analyzed through experimental tests of a constant-temperature water bath and numerical simulations. The result indicates that this PCM Ccylinder module is superior in thermal energy storage compared with the reference module even though fewer PCM was contained and the latent heat loss is considerable. The pipe diameter is an important parameter when using this kind of PCM cylinder module in water tanks.