Fabrication and characterization of 3D-printed composite scaffolds of coral-derived hydroxyapatite nanoparticles/polycaprolactone/gelatin carrying doxorubicin for bone tissue engineering

In this study, nanocomposite scaffolds of hydroxyapatite (HA)/polycaprolactone (PCL)/gelatin (Gel) with varying amounts of HA (42-52 wt. %), PCL (42-52 wt. %), and Gel (6 wt. %) were 3D printed. Subsequently, a scaffold with optimal mechanical properties was utilized as a carrier for doxorubicin (DOX) in the treatment of bone cancer. For this purpose, HA nanoparticles were first synthesized by the hydrothermal conversion of Acropora coral and characterized by using different techniques. Also, a compression test was performed to investigate the mechanical properties of the fabricated scaffolds. The mineralization of the optimal scaffold was determined by immersing it in simulated body fluid (SBF) solution for 28 days, and the biocompatibility was investigated by seeding MG-63 osteoblast-like cells on it after 1-7 days. The obtained results showed that the average size of the synthesized HA particles was about 80 nm. The compressive modulus and strength of the scaffold with 47 wt. % HA was reported to be 0.29 GPa and 9.9 MPa, respectively, which was in the range of trabecular bones. In addition, the scaffold surface was entirely coated with an apatite layer after 28 days of soaking in SBF. Also, the efficiency and loading percentage of DOX were obtained as 30.8 and 1.6%, respectively. The drug release behavior was stable for 14 days. Cytotoxicity and adhesion evaluations showed that the fabricated scaffold had no negative effects on the viability of MG-63 cells and led to their proliferation during the investigated period. From these results, it can be concluded that the HA/PCL/Gel scaffold prepared in this study, in addition to its drug release capability, has good bioactivity, mechanical properties, and biocompatibility, and can be considered a suitable option for bone tumor treatment.

Isolation and characterization of human periodontal ligament stem cells under the terms of use in clinical application: A pilot study

Background

The aim of the present study is to determine the possibility of isolation and characterization of the human periodontal ligament stem cells (hPDLSCs) using limited harvested periodontal ligament (PDL) tissue of only one patient's wisdom teeth (2-4 teeth) under the more compatible terms of use in clinical application without using the fetal bovine serum (FBS).

Materials and Methods

In this pilot study, hPDLSCs were isolated from the impacted third molar, and tissue was scraped from the roots of the impacted third molar of 10 volunteers to enzymatically digest using collagenase. The cells were sub-cultured. The samples of the first seven patients and half of the eighth patient's sample were cultured in alpha modified of Eagle's medium (α-MEM) (-FBS) medium and the other part of the eighth patient's sample was cultured with prior medium supplemented with +FBS 15% as a control of the cultivation protocol. While for the past two patients (9th and 10th the α-MEM medium was supplemented with L-Glutamine, anti/anti 2X, and 20% knock-out serum replacement (KSR). Two more nutritious supplements (N2 and B27) were added to the medium of the tenth sample. Flow-cytometric analysis for the mesenchymal stem cell surface markers CD105, CD45, CD90, and CD73 was performed. Subsequent polymerase chain reaction was undertaken on three samples cultured with two growth media.

Results

Cultivation failed in some of the samples because of the lack of cell adhesion to the culturing dish bottom (floating cells), but it was successful for the 9th and 10th patients, which were cultured in the α-MEM serum supplemented with KSR 20%. Flow cytometry analysis was positive for CD105, CD90, and CD73 and negative for CD45. The PDL stem cells (PDLSCs) expressed CD105, CD45, and CD90 but were poor for CD73.

Conclusion

According to the limited number of sample tests in this study, isolation and characterization of PDLSCs from collected PDL tissue of one patient's wisdom teeth (2-4) may be possible by the proper setup in synthetic FBS-free serum.

In vivo evaluation of bone regeneration using ZIF8-modified polypropylene membrane in rat calvarium defects

AIM

The profound potential of zeolitic imidazolate framework 8 (ZIF8) thin film for inducing osteogenesis has been previously established under in vitro conditions. As the next step towards the clinical application of ZIF8-modified substrates in periodontology, this in vivo study aimed to evaluate the ability of the ZIF8 crystalline layer to induce bone regeneration in an animal model defect.

MATERIALS AND METHODS

Following the mechanical characterization of the membranes and analysing the in vitro degradation of the ZIF8 layer, in vivo bone regeneration was evaluated in a critical-sized (5-mm) rat calvarial bone defect model. For each animal, one defect was randomly covered with either a polypropylene (PP) or a ZIF8-modified membrane (n = 7 per group), while the other defect was left untreated as a control. Eight weeks post surgery, bone formation was assessed by microcomputed tomography scanning, haematoxylin and eosin staining and immunohistochemical analysis.

RESULTS

The ZIF8-modified membrane outperformed the PP membrane in terms of mechanical properties and revealed a trace Zn+2 release. Results of in vivo evaluation verified the superior barrier function of the ZIF8-coated membrane compared with pristine PP membrane. Compared with the limited marginal bone formation in the control and PP groups, the defect area was almost filled with mature bone in the ZIF8-coated membrane group.

CONCLUSIONS

Our results support the effectiveness of the ZIF8-coated membrane as a promising material for improving clinical outcomes of guided bone regeneration procedures, without using biological components.

Pumpless deterministic lateral displacement separation using a paper capillary wick

Deterministic lateral displacement (DLD) is a passive separation method that separates particles by hydrodynamic size. This label-free method is a promising technique for cell separation because of its high size resolution and insensitivity to flow rate. Development of capillary-driven microfluidic technologies allows microfluidic devices to be operated without any external power for fluid pumping, lowering their total cost and complexity. Herein, we develop and test a DLD-based particle and cell sorting method that is driven entirely by capillary pressure. We show microchip self-filling, flow focusing, flow stability, and capture of separated particles. We achieve separation efficiency of 92% for particle-particle separation and more than 99% efficiency for cell-particle separation. The high performance of driven flow and separation along with simplicity of the operation and setup make it a valuable candidate for point-of-care devices.

Biotechnological advancements towards water, food and medical healthcare: A review

The global health status is highly affected by the growing pace of urbanization, new lifestyles, climate changes, and resource exploitation. Modern technologies pave a promising way to deal with severe concerns toward sustainable development. Herein, we provided a comprehensive review of some popular biotechnological advancements regarding the progress achieved in water, food, and medicine, as the most substantial fields related to public health. The emergence of novel organic/inorganic materials has brought about significant improvement in conventional water treatment techniques, anti-fouling approaches, anti-microbial agents, food processing, biosensors, drug delivery systems, and implants. Particularly, a growing interest has been devoted to nanomaterials and their application for developing novel structures or improving the characteristics of standard components. Also, bioinspired materials have been widely used to improve the performance, efficiency, accuracy, stability, safety, and cost-effectiveness of traditional systems. On the other side, the fabrication of innovative devices for precisely monitoring and managing various ecosystem and human health issues is of great importance. Above all, exceptional advancements in designing ion-selective electrodes (ISEs), microelectromechanical systems (MEMs), and implantable medical devices have altered the future landscape of environmental and biomedical research. This review paper aimed to shed light on the wide-ranging materials and devices that have been developed for health applications and mainly focused on the impact of nanotechnology in this field.

Cellular Behaviors of Periodontal Ligament Stem Cells in the Presence of Bone Grafting Biomaterials, In-Vitro Study

Periodontal regeneration through the employment of bone substitutes has become a feasible strategy in animal and clinical studies. In this regard, we aimed to compare the periodontal ligament stem cell behavior in the vicinity of various bone grafting substitutes. Three types of popular bone substitutes, including allografts (Regen), xenografts (Cerabone), and alloplasts (Osteon) were studied in this experimental survey. The cellular attachment was assessed after four hours using the MTS assay and SEM imaging. In addition, cellular proliferation was investigated after 1, 3, 5, and 7 days through MTS assay. Osteogenesis was studied after 21 days of cell culture in a differentiation medium (DM+) and a normal medium (DM-), by employing real-time PCR and alizarin red staining. The highest cellular attachment was seen in the xenograft group with a significant difference in comparison to the other grafting materials. Despite the relatively low primary attachment of cells to allografts, the allograft group showed the highest total proliferation rate, while the lowest proliferation capacity was found in the alloplast group. Osteogenesis fount to be accelerated mostly by xenografts in both mediums (DM+ and DM-) after 3 weeks, while alloplasts showed the lowest osteogenesis. This study revealed that the type of bone substitutes used in regenerative treatments can affect cellular behavior and as a whole allografts and xenografts showed better results.

Assessment of Cytotoxicity and Odontogenic/Osteogenic Differentiation Potential of Nano-Dentine Cement Against Stem Cells from Apical Papilla

OBJECTIVE

Assessment of the cytotoxicity of novel calcium silicate-based cement is imperative in endodontics. This experimental study aimed to assess the cytotoxicity and odontogenic/osteogenic differentiation potential of a new calcium silicate/pectin cement called Nano-dentine against stem cells from the apical papilla (SCAPs).

MATERIALS AND METHODS

In this experimental study, the cement powder was synthesized by the sol-gel technique. Zirconium oxide was added as opacifier and Pectin, a plant-based polymer, and calcium chloride as the liquid to prepare the nano-based dental cement. Thirty-six root canal dentin blocks of human extracted single-canal premolars with 2 mm height, flared with #1, 2 and 3 Gates-Glidden drills were used to prepare the cement specimens. The cement, namely mineral trioxide aggregate (MTA), Biodentine, and the Nano-dentine were mixed according to the manufacturers' instructions and applied to the roots of canal dentin blocks. The cytotoxicity and odontogenic/osteogenic potential of the cement were evaluated by using SCAPs.

RESULTS

SCAPs were characterized by the expression of routine mesenchymal cell markers and differentiation potential to adipocytes, osteoblasts, and chondrocytes. Cement displayed no significant differences in cytotoxicity or calcified nodules formation. Gene expression analysis showed that all three types of cement induced significant down- regulation of COLA1; however, the new cement induced significant up-regulation of RUNX2 and SPP1 compared to the control group and MTA. The new cement also induced significant up-regulation of TGFB1 and inducible nitric oxide synthase (iNOS) compared with Biodentine and MTA.

CONCLUSION

The new Nano-dentin cement has higher odontogenic/osteogenic potential compared to Biodentine and MTA for differentiation of SCAPs to adipocytes, osteoblasts, and chondrocytes.

Optimizing Tenogenic Differentiation of Equine Adipose-Derived Mesenchymal Stem Cells (eq-ASC) Using TGFB3 Along with BMP Antagonists

OBJECTIVE

Tendon repair strategies usually are accompanied by pathological mineralization and scar tissue formation that increases the risk of re-injuries. This study aimed to establish an efficient tendon regeneration method simultaneously with a reduced risk of ectopic bone formation.

MATERIALS AND METHODS

In this experimental study, tenogenic differentiation was induced through transforming growth factor- β3 (TGFB3) treatment in combination with the inhibiting concentrations of bone morphogenetic proteins (BMP) antagonists, gremlin-2 (GREM2), and a Wnt inhibitor, namely sclerostin (SOST). The procedure's efficacy was evaluated using real-time polymerase chain reaction (qPCR) for expression analysis of tenogenic markers and osteochondrogenic marker genes. The expression level of two tenogenic markers, SCX and MKX, was also evaluated by immunocytochemistry. Sirius Red staining was performed to examine the amounts of collagen fibers. Moreover, to investigate the impact of the substrate on tenogenic differentiation, the nanofibrous scaffolds that highly resemble tendon extracellular matrix was employed.

RESULTS

Aggregated features formed in spontaneous normal culture conditions followed by up-regulation of tenogenic and osteogenic marker genes, including SCX, MKX, COL1A1, RUNX2, and CTNNB1. TGFB3 treatment exaggerated morphological changes and markedly amplified tenogenic differentiation in a shorter period of time. Along with TGFB3 treatment, inhibition of BMPs by GREM2 and SOST delayed migratory events to some extent and dramatically reduced osteo-chondrogenic markers synergistically. Nanofibrous scaffolds increased tenogenic markers while declining the expression of osteo-chondrogenic genes.

CONCLUSION

These findings revealed an appropriate in vitro potential of spontaneous tenogenic differentiation of eq- ASCs that can be improved by simultaneous activation of TGFB and inhibition of osteoinductive signaling pathways.

Comparison of Adhesion and Proliferation of Human Gingival Fibroblasts on Acellular Dermal Matrix with and without Low Level Diode Laser Irradiation, an in vitro Study

Statement of the Problem

In recent years, regeneration of periodontal soft tissues in the reconstruction of periodontal defects and the finding of suitable membranes and graft materials for the placement of autogenous grafts have been of great interest in various studies. In this regard, the proliferation and adhesion of regenerative cells are two linchpins of the complete regenerative process.

Purpose

This study aimed to evaluate the effects of low-level laser beams on the attachment and the proliferation of human gingival fibroblasts in the presence of acellular dermal matrix (ADM).

Materials and Method

All the experiments were conducted compared to tissue culture plate in four groups as follows: (1) Fibroblast+ADM+laser, (2) Fibroblast+ADM+ no laser, (3) Fibroblast + laser radiation, and (4) Fibroblast+ no laser. In this experimental study, the primary attachment was evaluated by passing 8h from seeding of 5×10⁵ gingival fibroblasts with or without a single dose (15.6 J/cm²) of laser radiation. Cell proliferation rate was also examined at 24, 48, and 72 hours after cell culture, following exposure to 5.2 J/cm² of laser at each day of examination. Thereafter, fibroblasts were incubated under the normal culture condition (at 37°C, 5% CO₂) in high glucose Dulbecco's Modified Eagle's medium (DMEM) medium supplemented with 10% fetal bovine serum, 1% glutamax, and 1% penicillin/streptomycin. Subsequently, the cellular viability was assessed on each time point using MTS calorimetric assay. The obtained data were statistically analyzed by applying ANOVA and Tukey tests.

Results

There was a significant difference among the means of these four groups in terms of the proliferation of fibroblasts at 24, 48 and 72 hours (p< 0.001). Moreover, there was no significant difference among the means of two groups in terms of fibroblastic attachment in 8 hours (p< 0.2). The fibroblast group has shown the highest proliferation rate among all groups after laser radiation.

Conclusion

It was indicated that the laser radiation increases the fibroblast cell proliferation. Accordingly, although this increase was higher in the fibroblast group alone compared to the fibroblasts cultured on acellular dermal matrix, the laser radiation did not significantly increase the attachment of fibroblast cells to acellular dermal matrix.

In Vitro Study of the Recruitment and Expansion of Mesenchymal Stem Cells at the Interface of a Cu-Doped PCL-Bioglass Scaffold

Developing new barrier membranes with improved biomechanical characteristics has acquired much interest owing to their crucial role in the field of periodontal tissue regeneration. In this regard, we enriched the electrospun polycaprolactone (PCL)/gelatin (Gel) membranes by adding bioglass (BG) or Cu-doped bioglass (CuBG) and examined their cellular adhesion and proliferation potential in the presence of alveolar bone marrow-derived mesenchymal stem cells (aBMSCs). The membranes were fabricated and characterized using mechanical strength, SEM, FTIR, EDX, and ICP assay. Besides, aBMSCs were isolated, characterized, and seeded with a density of 35,000 cells in each experimental group. Next, the cellular morphology, cell adhesion capacity, proliferation rate, and membrane antibacterial activity were assessed. The results displayed a significant improvement in the wettability, pore size, and Young’s modulus of the PCL membrane following the incorporation of gelatin and CuBG particles. Moreover, all scaffolds exhibited reasonable biocompatibility and bioactivity in physiological conditions. Although the PCL/Gel/CuBG membrane revealed the lowest primary cell attachment, cells were grown properly and reached the confluent state after seven days. In conclusion, we found a reasonable level of attachment and proliferation of aBMSCs on all modified membranes. Meanwhile, a trace amount of Cu provided superiority for PCL/Gel/CuBG in periodontal tissue regeneration.

Recent advances in polymeric nanostructured ion selective membranes for biomedical applications

Nano structured ion-selective membranes (ISMs) are very attractive materials for a wide range of sensing and ion separation applications. The present review focuses on the design principles of various ISMs; nanostructured and ionophore/ion acceptor doped ISMs, and their use in biomedical engineering. Applications of ISMs in the biomedical field have been well-known for more than half a century in potentiometric analysis of biological fluids and pharmaceutical products. However, the emergence of nanotechnology and sophisticated sensing methods assisted in miniaturising ion-selective electrodes to needle-like sensors that can be designed in the form of implantable or wearable devices (smartwatch, tattoo, sweatband, fabric patch) for health monitoring. This article provides a critical review of recent advances in miniaturization, sensing and construction of new devices over last decade (2011-2021). The designing of tunable ISM with biomimetic artificial ion channels offered intensive opportunities and innovative clinical analysis applications, including precise biosensing, controlled drug delivery and early disease diagnosis. This paper will also address the future perspective on potential applications and challenges in the widespread use of ISM for clinical use. Finally, this review details some recommendations and future directions to improve the accuracy and robustness of ISMs for biomedical applications.

AC electrokinetic isolation and detection of extracellular vesicles from dental pulp stem cells: Theoretical simulation incorporating fluid mechanics

Extracellular vesicles (EVs) are cell-derived nanoscale vesicles involved in intracellular communication and the transportation of biomarkers. EVs released by mesenchymal stem cells have been recently reported to play a role in cell-free therapy of many diseases. However, the demand for better research tools to replace the tedious conventional methods used to study EVs is getting stronger. EVs' manipulation using alternating current (AC) electrokinetic forces in a microfluidic device has appeared to be a reliable and sensitive diagnosis and trapping technique. Given that different AC electrokinetic forces may contribute to the overall motion of particles and fluids in a microfluidic device, EVs' electrokinetic trapping must be examined considering all dominant forces involved depending on the experimental conditions. In this paper, AC electrokinetic trapping of EVs using an interdigitated electrode arrays is investigated. A 2D numerical simulation incorporating the two significant AC electrokinetic phenomena (Dielectrophoresis and AC electroosmosis) has been performed. Theoretical predictions are then compared with experimental results and allow for a plausible explanation of observations inconsistent with DEP theory. It is demonstrated that the inconsistencies can be attributed to a significant extent to the contribution of the AC electroosmotic effect.

Enhancing osteoregenerative potential of biphasic calcium phosphates by using bioinspired ZIF8 coating

Biphasic calcium phosphate ceramics (BCPs) have been extensively used as a bone graft in dental clinics to reconstruct lost bone in the jaw and peri-implant hard tissue due to their good bone conduction and similar chemical structure to the teeth and bone. However, BCPs are not inherently osteoinductive and need additional modification and treatment to enhance their osteoinductivity. The present study aims to develop an innovative strategy to improve the osteoinductivity of BCPs using unique features of zeolitic imidazolate framework-8 (ZIF8). In this method, commercial BCPs (Osteon II) were pre-coated with a zeolitic imidazolate framework-8/polydopamine/polyethyleneimine (ZIF8/PDA/PEI) layer to form a uniform and compact thin film of ZIF8 on the surface of BCPs. The surface morphology and chemical structure of ZIF8 modified Osteon II (ZIF8-Osteon) were confirmed using various analytical techniques such as XRD, FTIR, SEM, and EDX. We evaluated the effect of ZIF8 coating on cell attachment, growth, and osteogenic differentiation of human adipose-derived mesenchymal stem cells (hADSCs). The results revealed that altering the surface chemistry and topography of Osteon II using ZIF8 can effectively promote cell attachment, proliferation, and bone regeneration in both in vitro and in vivo conditions. In conclusion, the method applied in this study is simple, low-cost, and time-efficient and can be used as a versatile approach for improving osteoinductivity and osteoconductivity of other types of alloplastic bone grafts.

ZIF-8 Modified Polypropylene Membrane: A Biomimetic Cell Culture Platform with a View to the Improvement of Guided Bone Regeneration

PURPOSE

Despite the significant advances in modeling of biomechanical aspects of cell microenvironment, it remains a major challenge to precisely mimic the physiological condition of the particular cell niche. Here, the metal-organic frameworks (MOFs) have been introduced as a feasible platform for multifactorial control of cell-substrate interaction, given the wide range of physical and mechanical properties of MOF materials and their structural flexibility.

RESULTS

In situ crystallization of zeolitic imidazolate framework-8 (ZIF-8) on the polydopamine (PDA)-modified membrane significantly raised surface energy, wettability, roughness, and stiffness of the substrate. This modulation led to an almost twofold increment in the primary attachment of dental pulp stem cells (DPSCs) compare to conventional plastic culture dishes. The findings indicate that polypropylene (PP) membrane modified by PDA/ZIF-8 coating effectively supports the growth and proliferation of DPSCs at a substantial rate. Further analysis also displayed the exaggerated multilineage differentiation of DPSCs with amplified level of autocrine cell fate determination signals, like BSP1, BMP2, PPARG, FABP4, ACAN, and COL2A. Notably, osteogenic markers were dramatically overexpressed (more than 100-folds rather than tissue culture plate) in response to biomechanical characteristics of the ZIF-8 layer.

CONCLUSION

Hence, surface modification of cell culture platforms with MOF nanostructures proposed as a powerful nanomedical approach for selectively guiding stem cells for tissue regeneration. In particular, PP/PDA/ZIF-8 membrane presented ideal characteristics for using as a barrier membrane for guided bone regeneration (GBR) in periodontal tissue engineering.

Recent developments in enzyme immobilization technology for high-throughput processing in food industries

The demand for food and beverage markets has increased as a result of population increase and in view of health awareness. The quality of products from food processing industry has to be improved economically by incorporating greener methodologies that enhances the safety and shelf life via the enzymes application while maintaining the essential nutritional qualities. The utilization of enzymes is rendered more favorable in industrial practices via the modification of their characteristics as attested by studies on enzyme immobilization pertaining to different stages of food and beverage processing; these studies have enhanced the catalytic activity, stability of enzymes and lowered the overall cost. However, the harsh conditions of industrial processes continue to increase the propensity of enzyme destabilization thus shortening their industrial lifespan namely enzyme leaching, recoverability, uncontrollable orientation and the lack of a general procedure. Innovative studies have strived to provide new tools and materials for the development of systems offering new possibilities for industrial applications of enzymes. Herein, an effort has been made to present up-to-date developments on enzyme immobilization and current challenges in the food and beverage industries in terms of enhancing the enzyme stability.

Development of a Highly Proliferated Bilayer Coating on 316L Stainless Steel Implants

In this research, a bilayer coating has been applied on the surface of 316 L stainless steel (316LSS) to provide highly proliferated metallic implants for bone regeneration. The first layer was prepared using electrophoretic deposition of graphene oxide (GO), while the top layer was coated utilizing electrospinning of poly (ε-caprolactone) (PCL)/gelatin (Ge)/forsterite solutions. The morphology, porosity, wettability, biodegradability, bioactivity, cell attachment and cell viability of the prepared coatings were evaluated. The Field Emission Scanning Electron Microscopy (FESEM) results revealed the formation of uniform, continuous, and bead-free nanofibers. The Energy Dispersive X-ray (EDS) results confirmed well-distributed forsterite nanoparticles in the structure of the top coating. The porosity of the electrospun nanofibers was found to be above 70%. The water contact angle measurements indicated an improvement in the wettability of the coating by increasing the amount of nanoparticles. Furthermore, the electrospun nanofibers containing 1 and 3 wt.% of forsterite nanoparticles showed significant bioactivity after soaking in the simulated body fluid (SBF) solution for 21 days. In addition, to investigate the in vitro analysis, the MG-63 cells were cultured on the PCL/Ge/forsterite and GO-PCL/Ge/forsterite coatings. The results confirmed an excellent cell adhesion along with considerable cell growth and proliferation. It should be also noted that the existence of the forsterite nanoparticles and the GO layer substantially enhanced the cell proliferation of the coatings.

3D Printing of Inertial Microfluidic Devices

Inertial microfluidics has been broadly investigated, resulting in the development of various applications, mainly for particle or cell separation. Lateral migrations of these particles within a microchannel strictly depend on the channel design and its cross-section. Nonetheless, the fabrication of these microchannels is a continuous challenging issue for the microfluidic community, where the most studied channel cross-sections are limited to only rectangular and more recently trapezoidal microchannels. As a result, a huge amount of potential remains intact for other geometries with cross-sections difficult to fabricate with standard microfabrication techniques. In this study, by leveraging on benefits of additive manufacturing, we have proposed a new method for the fabrication of inertial microfluidic devices. In our proposed workflow, parts are first printed via a high-resolution DLP/SLA 3D printer and then bonded to a transparent PMMA sheet using a double-coated pressure-sensitive adhesive tape. Using this method, we have fabricated and tested a plethora of existing inertial microfluidic devices, whether in a single or multiplexed manner, such as straight, spiral, serpentine, curvilinear, and contraction-expansion arrays. Our characterizations using both particles and cells revealed that the produced chips could withstand a pressure up to 150 psi with minimum interference of the tape to the total functionality of the device and viability of cells. As a showcase of the versatility of our method, we have proposed a new spiral microchannel with right-angled triangular cross-section which is technically impossible to fabricate using the standard lithography. We are of the opinion that the method proposed in this study will open the door for more complex geometries with the bespoke passive internal flow. Furthermore, the proposed fabrication workflow can be adopted at the production level, enabling large-scale manufacturing of inertial microfluidic devices.

Mussel inspired ZIF8 microcarriers: a new approach for large-scale production of stem cells

Metal–organic frameworks (MOFs) have high porosity, large surface area, and tunable functionality and have been widely used for drug loading. The aim of this study was to exploit unique features of zeolitic imidazolate framework-8 (ZIF8) to develop an innovative composite microcarrier (MC) for human mesenchymal stem cells (hMSCs) adhesion and proliferation. ZIF8 MCs were prepared by immobilization of polydopamine/polyethyleneimine (PDA/PEI) and ZIF8 on the surface of polystyrene beads. The chemical properties of MCs such as coating stability and homogeneity were characterized by different techniques such as ATR-FTIR, XRD, EDX, SEM, and contact angle. The prepared MCs were tested using human adipose-derived mesenchymal stem cells (hADSCs) in both static and dynamic conditions, and results were compared to a commercially available MC (Star-Plus), polydopamine coated MCs and amine-functionalized MCs as a control. Results show that PDA/PEI/ZIF8 coated MCs (in short: ZIF8 MCs) provides an excellent biocompatible environment for hADSCs adhesion and growth. In conclusion, ZIF8 MCs represent suitable and low-cost support for hADSCs culture and expansion, which can maximize cell yield and viability while preserving hADSCs multipotency. The present findings have revealed this strategy has the potential for chemical and topographical modification of MCs in tissue engineering applications.

Mussel inspired ZIF8 microcarriers with high surface area, biocompatibility, and nanoscale surface roughness are applied to enhance mesenchymal stem cell attachment and proliferation in 3D cell culture.

Cytotoxicity Evaluation of The Bioresorbable and Titanium Plates/Screws Used in Maxillofacial Surgery on Gingival Fibroblasts and Human Mesenchymal Bone Marrow Stem Cells

Objective

Bioresorbable and titanium plates/screws are considered as a standard treatment for fixation of the bone segments of craniofacial area and paying attention to their biocompatibility is an important issue along with other aspects of application. The purpose of the study was to evaluate the cell viability of two types of plate and screw used in maxillofacial surgeries in contact with gingival fibroblasts and bone marrow stem cells.

Materials and Methods

In this experimental study after extraction and cultivation of cells from healthy human gingival tissue and alveolar bone of jaw, cytotoxicity of device was evaluated. In direct contact method, samples had near vicinity contact with the both cell lines and in indirect contact method, by-products released, like ions, from samples after 8 weeks were used to assess cytotoxicity. Then cytotoxicity was evaluated on the 2^nd, 4^th and 6^th day with MTS tests and microscopy. The data were analyzed by one-way ANOVA and independent t tests.

Results

There was a statistically significant difference between the German plate and screw and all the samples studied on day 6 (P<0.05). Furthermore, a statistically significant difference was observed between both metal samples and both bio-absorbable samples on day 6 and both cell lines (P<0.05). Comparisons between the two groups with each other for both cell lines on the 6^th day were statistically significant (P<0.05).

Conclusion

Our results suggest that that cytotoxicity of biomaterial, from different brands, were not similar and some of the biomaterial showed lower degree of toxicity compared to others and specialist using these products showed be aware of this differences. Our investigation indicates more biocompatibility of bioresorbable plates and screws compared to titanium. In addition our results suggest that biomaterials were not completely neutral.

Activated platelet-rich plasma improves cartilage regeneration using adipose stem cells encapsulated in a 3D alginate scaffold

In the current study, the effect of superimposing platelet-rich plasma (PRP) on different culture mediums in a three-dimensional alginate scaffold encapsulated with adipose-derived mesenchymal stem cells for cartilage tissue repair is reported. The three-dimensional alginate scaffolds with co-administration of PRP and/or chondrogenic supplements had a significant effect on the differentiation of adipose mesenchymal stem cells into mature cartilage, as assessed by an evaluation of the expression of cartilage-related markers of Sox9, collagen II, aggrecan and collagen, and glycosaminoglycan assays. For in vivo studies, following induction of osteochondral lesion in a rabbit model, a high degree of tissue regeneration in the alginate plus cell group (treated with PRP plus chondrogenic medium) compared with other groups of cell-free alginate and untreated groups (control) were observed. After 8 weeks, in the alginate plus cell group, functional chondrocytes were observed, which produced immature matrix, and by 16 weeks, the matrix and hyaline-like cartilage became completely homogeneous and integrated with the natural surrounding cartilage in the defect site. Similar effect was also observed in the subchondral bone. The cell-free scaffolds formed fibrocartilage tissue, and the untreated group did not form a continuous cartilage over the defect by 16 weeks.

Equine adipose mesenchymal stem cells (eq-ASCs) appear to have higher potential for migration and musculoskeletal differentiation

Equine adipose-derived mesenchymal stem cells (eq-ASCs) possess excellent regeneration potential especially for treatment of musculoskeletal disorders. Besides their common characteristics, MSCs harvested from different species reveal some species-specific and donor-dependent behaviors. Hence, the molecular analysis of MSCs may shed more light on their future clinical application of these cells. This study aimed to investigate some behavioral aspects of eq-ASCs in vitro which may influence the efficacy of stem cell therapy. For this purpose, MSCs of a donor horse were isolated, characterized and expanded under normal culture conditions. During continuous culture condition, eq-ASCs were started to formed aggregated structures that was accompanied with the up-regulation of migratory related genes including transforming growth factor beta 1 (TGFB1) and its receptor 3 (TGFBR3), and snail family transcriptional repressor 1 (SNAI1), E-cadherin (CDH1) and β-catenin (CTNNB1). Moreover, the expression of a musculoskeletal progenitor marker, scleraxis bHLH transcription factor (SCX), was also increased after 3 days. In order to clarify the impact of TGFB signaling pathway on cultured cells, gain- and loss-of-function treatment by TGFB3 and SB431542 (TGFB inhibitor) were performed, respectively. We found that TGFB3 treatment exaggerated the aggregate formation effects, in some extend via induction of cytoskeletal actin rearrangement, while inhibition of TGFB signaling pathway by SB431542 reversed this phenomenon. Overall, our findings support the fact that eq-ASCs have an inherent capacity for migration, which was enhanced by TGFB3 treatment and, this ability may play crucial role in cell motility and wound healing of transplanted cells.

Hypothesis: A Challenge of Overexpression Zfp521 in Neural Tendency of Derived Dental Pulp Stem Cells

Neurodegenerative diseases have now become a major challenge, especially in aged societies. Most of the traditional strategies used for treatment of these diseases are untargeted and have little efficiency. Developments in stem cell investigations have given much attention to cell therapy as an alternative concept in the regeneration of neural tissues. Dental pulp stem cells (DPSCs) can be readily obtained by noninvasive procedures and have been shown to possess properties similar to well-known mesenchymal stem cells. Furthermore, based on their neural crest origin, DPSCs are considered to have a good potential to differentiate into neural cells. Zfp521 is a transcription factor that regulates expression of many genes, including ones involved in the neural differentiation process. Therefor based on neural crest origin of the cell and high expression of neural progenitor markers, we speculate that sole overexpression of Zfp521 protein can facilitate differentiation of dental stem cells to neural cells and researchers may find these cells suitable for therapeutic treatment of neurodegenerative diseases.

Hepatocyte growth factor promotes the proliferation of human embryonic stem cell derived retinal pigment epithelial cells

Research that pertains to the molecular mechanisms involved in retinal pigment epithelial (RPE) development can significantly contribute to cell therapy studies. The effects of periocular mesenchymal cells on the expansion of RPE cells remain elusive. We have examined the possible proliferative role of hepatocyte growth factor (HGF) as a mesenchymal cell secretory factor against human embryonic stem cell derived RPE (hESC-RPE). We found that the conditioned medium of human mesenchymal stem cells from apical papilla and/or exogenous HGF promoted proliferation of the hESC-RPE cells as single cells and cell sheets, in addition to rabbit RPE sheets in vitro. Blockage of HGF signaling by HGF receptor inhibitor, PHA-665752, inhibited proliferation of hESC-RPE cells. However, differentiation of hESCs and human-induced pluripotent stem cells to a rostral fate and eye-field specification was unaffected by HGF. Our in vivo analysis showed HGF expression in periocular mesenchymal cells after optic cup formation in chicken embryos. Administration of HGF receptor inhibitor at this developmental stage in chicken embryos led to reduced eye size and disorganization of the RPE sheet. These findings suggested that HGF administration could be beneficial for obtaining higher numbers of hESC-RPE cells in human preclinical and clinical trials.

Comparison of two digestion strategies on characteristics and differentiation potential of human dental pulp stem cells

OBJECTIVE

This study aimed to compare the behavior of dental pulp stem cells (DPSCs) after isolation using solutions containing either collagenase/dispase or collagenase alone.

DESIGN

DPSCs were isolated by two digestion methods (collagenase/dispase or collagenase alone) from human third molars. Immunophenotypic features were confirmed by flow cytometry for cell markers STRO-1, cluster of differentiation (CD) 146, CD45, and collagen type-I. The proliferation potential of cells was evaluated by 5-bromo-2'-deoxyuridine (brdU) incorporation assay, and finally they were assessed for multi-lineage differentiation potential. Data were analyzed using one-way analysis of variance and independent t-tests.

RESULTS

DPSCs isolated by either method showed similar levels of STRO-1, CD45, and collagen type-I and similar incorporation of brdU (P > 0.05). However, DPSCs obtained by collagenase I/dispase treatment had significantly higher numbers of CD146⁺ cells and osteogenic and chondrogenic capacities compared to those obtained by treatment with collagenase I alone (P < 0.05). On the other hand, more STRO-1+/CD164-DPSCs were found in the collagenase alone group with higher adipogenic potential.

CONCLUSIONS

Different enzyme solutions gave rise to different populations of DPSCs. Dispase enhanced isolation of CD146⁺ DPSCs probably by disrupting the basement membranes of blood vessels and releasing DPCSs embedded in the perivascular niche. Furthermore, the differentiation potential of DPSCs was influenced by the change in enzyme solution.

Highly degradable porous melt-derived bioactive glass foam scaffolds for bone regeneration

A challenge in using bioactive melt-derived glass in bone regeneration is to produce scaffolds with interconnected pores while maintaining the amorphous nature of the glass and its associated bioactivity. Here we introduce a method for creating porous melt-derived bioactive glass foam scaffolds with low silica content and report in vitro and preliminary in vivo data. The gel-cast foaming process was adapted, employing temperature controlled gelation of gelatin, rather than the in situ acrylic polymerisation used previously. To form a 3D construct from melt derived glasses, particles must be fused via thermal processing, termed sintering. The original Bioglass® 45S5 composition crystallises upon sintering, altering its bioactivity, due to the temperature difference between the glass transition temperature and the crystallisation onset being small. Here, we optimised and compared scaffolds from three glass compositions, ICIE16, PSrBG and 13-93, which were selected due to their widened sintering windows. Amorphous scaffolds with modal pore interconnect diameters between 100-150µm and porosities of 75% had compressive strengths of 3.4±0.3MPa, 8.4±0.8MPa and 15.3±1.8MPa, for ICIE16, PSrBG and 13-93 respectively. These porosities and compressive strength values are within the range of cancellous bone, and greater than previously reported foamed scaffolds. Dental pulp stem cells attached to the scaffold surfaces during in vitro culture and were viable. In vivo, the scaffolds were found to regenerate bone in a rabbit model according to X-ray micro tomography imaging.

STATEMENT OF SIGNIFICANCE

This manuscript describes a new method for making scaffolds from bioactive glasses using highly bioactive glass compositions. The glass compositions have lower silica content that those that have been previously made into amorphous scaffolds and they have been designed to have similar network connectivity to that of the original (and commercially used) 45S5 Bioglass. The aim was to match Bioglass' bioactivity. The scaffolds retain the amorphous nature of bioactive glass while having an open pore structure and compressive strength similar to porous bone (the original 45S5 Bioglass crystallises during sintering, which can cause reduced bioactivity or instability). The new scaffolds showed unexpectedly rapid bone regeneration in a rabbit model.

Hedgehog signalling is dispensable in the proliferation of stem cells from human exfoliated deciduous teeth

The hedgehog (Hh) signalling pathway is one of the key regulators in development with a dual role in cell fate specification, proliferation, and survival on different target cells. We have investigated the effect of recombinant sonic hedgehog (r-SHH) on extracted multipotent stem cells from human exfoliated deciduous teeth (SHED), which represent a potential stem cell population for therapeutic applications. Cell proliferation and cycle assays shown that r-SHH did not have a distinctive effect on cell cycle progression, nor did it increase cell number over a wide range of concentrations. Quantitative polymerase chain reaction (Q-PCR) also suggests that r-SHH treatment has no demonstrable influence on expression of proliferative genes (CCNE1 and KI67); in contrast, the anti-proliferative gene (CDKN1A) is overexpressed in response to SHH. Our findings have suggested the possibility that SHEDs demonstrate a different potential from human bone marrow mesenchymal stem cells (h-BMSCs) and dorsal neural progenitor in response to growth factors such as SHH.