3D Printing: Advancement in Biogenerative Engineering to Combat Shortage of Organs and Bioapplicable Materials

Role of cell-based therapies in digestive disorders: Obstacles and opportunities

Stem cell-based therapies have emerged as a promising frontier in the treatment of gastrointestinal disorders, offering potential solutions for challenges posed by conventional treatments. This review comprehensively examines recent advancements in cell-based therapeutic strategies, particularly focusing on stem cell applications, immunotherapy, and cellular therapies for digestive diseases. It highlights the successful differentiation of enteric neural progenitors from pluripotent stem cells and their application in animal models, such as Hirschsprung disease. Furthermore, the review evaluates clinical trials and experimental studies demonstrating the potential of stem cells in regenerating damaged tissues, modulating immune responses, and promoting healing in conditions like Crohn's disease and liver failure. By addressing challenges, such as scalability, immunogenicity, and ethical considerations, the review underscores the translational opportunities and obstacles in realizing the clinical potential of these therapies. Concluding with an emphasis on future directions, the study provides insights into optimizing therapeutic efficacy and fostering innovations in personalized medicine for digestive disorders.

Extrusion bioprinting: meeting the promise of human tissue biofabrication?

Extrusion is the most popular bioprinting platform. Predictions of human tissue and whole-organ printing have been made for the technology. However, after decades of development, extruded constructs lack the essential microscale resolution and heterogeneity observed in most human tissues. Extrusion bioprinting has had little clinical impact with the majority of research directed away from the tissues most needed by patients. The distance between promise and reality is a result of technology hype and inherent design flaws that limit the shape, scale and survival of extruded features. By more widely adopting resolution innovations and softening its ambitions the biofabrication field could define a future for extrusion bioprinting that more closely aligns with its capabilities.

Assessing the landscape of clinical and observational trials involving bioprinting: a scoping review

OBJECTIVE

Bioprinting is a tissue engineering technique that is rapidly evolving to include complex clinical applications. However, there is limited evidence describing how far bioprinting has progressed past the pre-clinical stage. Thus, we conducted a scoping review to assess the landscape of clinical studies, including interventional and observational trials, involving bioprinting by charting trends in general characteristics, bioprinting application, and trial design.

METHODS

The term "bioprint" and its variants were searched in five trial databases (ICTRP, ScanMedicine, CENTRAL, NIHCC, HCCTD) and two registries (ClinicalTrials.gov, PHRR) on 22 February 2024. This was followed by duplicate removal and dual independent review to finalize the inclusion list. We included trials published in or translated to English mentioning "bioprint" in their design, while we excluded those that did not adhere to our definition of bioprinting. Finally, data were charted and synthesized narratively.

RESULTS

Of 36 total search records, 11 trials met the inclusion criteria. Registration dates ranged from 2016 to 2023, with China conducting the most trials globally. Four trials had published results, while the remaining were still in progress. Four interventional trials aimed to implant bioprinted tissues made with autologous cells, including blood vessels, trachea, external ear, and wound dressings. The other seven studies were interventional and observational trials aiming to bioprint autologous cell-laden in vitro models to study conditions such as cancer.

CONCLUSION

Bioprinting is still in the early stages of clinical research, with a focus on producing patient-specific tissues for cancer precision medicine and regenerative purposes. More standardized reporting of bioprinting-related information is needed to improve research transparency and replicability. As the body of evidence grows, our review may be used as a framework to monitor the clinical translation of bioprinting over the years.

3D Bioprinting of Pig Macrophages and Human Cells Discovered the P2Y14 Receptor as a Mediator of Xenogenic Immune Responses

BACKGROUND

The survival rate of pig lung xenotransplantation (PLXTx) recipients is severely limited by intense xenogenic immune responses, necessitating further insights into xenogeneic immunity and the development of models to study the PLXTx immune response.

METHODS

We identified regulators of PLXTx immune response Using Gene ontology analysis. We assessed the metabolic changes and protein levels in 3D4/31 pig alveolar macrophages (PAMs) through flow cytometry and immunoblotting. To induce a xenogenic immune response, we co-cultured 3D4/31-PAMs with A549 human alveolar epithelial cells and evaluated cytokine expression using qRT-PCR.

RESULTS

Gene ontology analysis identified STAT1 and alveolar macrophages as contributors to lung autoimmunity and transplant rejection. In 3D4/31-PAMs, phorbol myristate acetate-induced glycogen accumulation and cyclooxygenase-2 expression were inhibited by the P2Y14 inhibitor PPTN. Co-culturing 3D4/31-PAMs with A549 human alveolar epithelial cells via 3D bioprinting resulted in a more pronounced inflammatory response than 2D co-culture, with increased expression of genes related to the P2Y14 cascade and inflammation. This inflammatory gene expression was prevented by PPTN treatment.

CONCLUSION

Based on these results, we propose alginate bioprinting as an in vitro model for PLXTx and suggest that P2Y14 is a key regulator of xenogeneic immune responses in PAMs.

Advances in Injectable Polymeric Biomaterials and Their Contemporary Medical Practices

Injectable biomaterials have been engineered to operate within the human body, offering versatile solutions for minimally invasive therapies and meeting several stringent requirements such as biocompatibility, biodegradability, low viscosity for ease of injection, mechanical strength, rapid gelation postinjection, controlled release of therapeutic agents, hydrophobicity/hydrophilicity balance, stability under physiological conditions, and the ability to be sterilized. Their adaptability and performance in diverse clinical settings make them invaluable for modern medical treatments. This article reviews recent advancements in the design, synthesis, and characterization of injectable polymeric biomaterials, providing insights into their emerging applications. We discuss a broad spectrum of these materials, including natural, synthetic, hybrid, and composite types, that are being applied in targeted drug delivery, cell and protein transport, regenerative medicine, tissue adhesives, injectable implants, bioimaging, diagnostics, and 3D bioprinting. Ultimately, the review highlights the critical role of injectable polymeric biomaterials in shaping the future of medical treatments and improving patient outcomes across a wide range of therapeutic and diagnostic applications.

Engineered Skin Substitutes in Dermatologic Surgery: A Systematic Review

BACKGROUND

Artificial skin substitutes are a flexible alternative to autografting in Mohs micrographic surgery (MMS), but the characteristics and clinical outcomes of skin substitutes are not well defined.

OBJECTIVE

Summarize clinical data of skin substitutes in MMS for cutaneous malignancy.

METHODS

A MEDLINE/Embase/Web of Science search was conducted. Articles with original data on outcomes after skin substitute use in MMS for cutaneous malignancy were included. Articles not in English or without original data were excluded. Bias was assessed using the Oxford CEBM Levels of Evidence Table. Outcomes were synthesized using weighted averages. This study was prospectively registered in PROSPERO.

RESULTS

Of 1,007 articles, 40 met eligibility for inclusion. In total, 898 patients who underwent MMS and received a skin substitute were included. Xenografts were most commonly used ( n = 613). Semi-synthetic grafts (∼$<1/cm 2 ) and xenografts (∼$10/cm 2 ) are most affordable. Overall, outcomes were excellent for all skin substitutes, with a small proportion of patients experiencing correctable complications.

CONCLUSION

Skin substitutes are highly effective in MMS, with enormous potential. While the data demonstrate positive outcomes, they predominately draw from small, retrospective studies or case reports. There is also a scarcity of data comparing skin substitutes with each other or controls. Prospective studies are recommended.

Evaluating different methods for kidney recellularization

This study explores a potential solution to the shortage of kidneys for transplantation in end-stage renal disease (ESRD). Currently, kidney transplantation stands as the optimal option, yet the scarcity of organs persists. Employing tissue engineering, researchers sought to assess the feasibility of generating kidneys for transplantation. Pig kidneys were utilized since they possess higher similarities to human kidneys. Cells were removed via decellularization, which maintains the organ's microarchitecture. Subsequently, pig kidney cells and human red blood cells were perfused into the vacant kidney structure to reconstitute it. The methodologies employed showed promising results, suggesting a viable approach to increase the recellularization rate in whole pig kidneys. This proof-of-concept establishes a groundwork for potentially extending this technology to human kidneys, tackling the organ shortage, thus positively enhancing outcomes for ESRD patients by increasing the availability of transplantable organs.

Prototyping in Polymethylpentene to Enable Oxygen-Permeable On-a-Chip Cell Culture and Organ-on-a-Chip Devices Suitable for Microscopy

With the rapid development and commercial interest in the organ-on-a-chip (OoC) field, there is a need for materials addressing key experimental demands and enabling both prototyping and large-scale production. Here, we utilized the gas-permeable, thermoplastic material polymethylpentene (PMP). Three methods were tested to prototype transparent PMP films suitable for transmission light microscopy: hot-press molding, extrusion, and polishing of a commercial, hazy extruded film. The transparent films (thickness 20, 125, 133, 356, and 653 µm) were assembled as the cell-adhering layer in sealed culture chamber devices, to assess resulting oxygen concentration after 4 days of A549 cell culture (cancerous lung epithelial cells). Oxygen concentrations stabilized between 15.6% and 11.6%, where the thicker the film, the lower the oxygen concentration. Cell adherence, proliferation, and viability were comparable to glass for all PMP films (coated with poly-L-lysine), and transparency was adequate for transmission light microscopy of adherent cells. Hot-press molding was concluded as the preferred film prototyping method, due to excellent and reproducible film transparency, the possibility to easily vary film thickness, and the equipment being commonly available. The molecular orientation in the PMP films was characterized by IR dichroism. As expected, the extruded films showed clear orientation, but a novel result was that hot-press molding may also induce some orientation. It has been reported that orientation affects the permeability, but with the films in this study, we conclude that the orientation is not a critical factor. With the obtained results, we find it likely that OoC models with relevant in vivo oxygen concentrations may be facilitated by PMP. Combined with established large-scale production methods for thermoplastics, we foresee a useful role for PMP within the OoC field.

Variations in the Thermomechanical and Structural Properties during the Cooling of Shape-Memory R-PETG

One of the useful features of 3D-printed specimens of recycled polyethylene terephthalate glycol (R-PETG) is the ability to repetitively develop free recovery as well as the work-generating, shape-memory effect. This behavior is enabled by the R-PETG's capacity to stiffen during cooling, thus allowing for a new temporary shape to be induced. Aiming to devise an explanation for the polymer's stiffening, in this study, the variation in some of the R-PETG's parameters during cooling are emphasized and discussed. The evolution of an R-PETG filament's shape was monitored during room-temperature-bending heating-cooling cycles. Straight-shape recovery and the complete loss of stiffness were observed at the start and the end of heating, respectively, followed by the forced straightening of the filament, performed by the operator, around 40 °C, during cooling. The tests performed by dynamic mechanical analysis disclosed the rise of the storage modulus (E') after 100 °C heating followed by either liquid-nitrogen- or air-cooling to room temperature, in such a way that E' was always larger after cooling than initially. Static tests emphasized a peculiar stress variation during a heating-cooling cycle applied in air, within the heating chamber of the tensile testing machine. Tensile-failure tests were performed at -10 °C at a rate of 100 mm/min, with specimens printed at various deposition directions between 10 and 40° to the transversal direction. The specimens printed at 40°, which had the largest ultimate strains, were broken with tensile rates between 100 and 500 mm/min. Deformation rate increase favored the shift from crazing to delamination failure modes. The correlation between the structural changes, the sharp E' increase on heating, and the stiffening induced by cooling represents a novel approach that enables the use of 3D-printed R-PETG for the fabrication of the active parts of low-priced lightweight resettable actuators.

Extracellular matrix of lung scaffolds submitted to different means of sterilization: a systematic review

Chronic respiratory diseases often necessitate lung transplantation due to irreversible damage. Organ engineering offers hope through stem cell-based organ generation. However, the crucial sterilization step in scaffold preparation poses challenges. This study conducted a systematic review of studies that analysed the extracellular matrix (ECM) conditions of decellularised lungs subjected to different sterilisation processes. A search was performed for articles published in the PubMed, Web of Sciences, Scopus, and SciELO databases according to the PRISMA guidelines. Overall, five articles that presented positive results regarding the effectiveness of the sterilisation process were selected, some of which identified functional damage in the ECM. Was possible concluded that regardless of the type of agent used, physical or chemical, all of them demonstrated that sterilisation somehow harms the ECM. An ideal protocol has not been found to be fully effective in the sterilisation of pulmonary scaffolds for use in tissue and/or organ engineering.

Heterogeneous and Composite Bioinks for 3D-Bioprinting of Complex Tissue

Bioink composition is a key consideration for the 3D-bioprinting of complex and stable structures used to model tissues and as tissue constructs for regenerative medicine. An emerging and industrially important area of research is the use of micro- and nanofillers to improve bioink performance without dramatically altering the physicochemical properties of the polymeric material that forms the bulk of the printed structure. The purpose of this review is to provide a comprehensive overview of emerging nanomaterial fillers designed to create heterogeneous and composite bioinks for 3D-bioprinting of complex functional tissues. We outline the criteria that must be considered when developing such a bioink and discuss applications where the fillers impart stimuli responsiveness, e.g., when exposed to magnetic fields, electrical fields, and light. We further highlight how the use of such fillers can enable non-destructive imaging to monitor scaffold placement and integrity following implantation.

Recent Advances in Alginate-Based Hydrogels for Cell Transplantation Applications

With its exceptional biocompatibility, alginate emerged as a highly promising biomaterial for a large range of applications in regenerative medicine. Whether in the form of microparticles, injectable hydrogels, rigid scaffolds, or bioinks, alginate provides a versatile platform for encapsulating cells and fostering an optimal environment to enhance cell viability. This review aims to highlight recent studies utilizing alginate in diverse formulations for cell transplantation, offering insights into its efficacy in treating various diseases and injuries within the field of regenerative medicine.

Progress in cardiac tissue engineering and regeneration: Implications of gelatin-based hybrid scaffolds

Cardiovascular diseases, particularly myocardial infarction (MI), remain a leading cause of morbidity and mortality worldwide. Current treatments for MI, more palliative than curative, have limitations in reversing the disease completely. Tissue engineering (TE) has emerged as a promising strategy to address this challenge and may lead to improved therapeutic approaches for MI. Gelatin-based scaffolds, including gelatin and its derivative, gelatin methacrylate (GelMA), have attracted significant attention in cardiac tissue engineering (CTE) due to their optimal physical and biochemical properties and capacity to mimic the native extracellular matrix (ECM). CTE mainly recruits two classes of gelatin/GelMA-based scaffolds: hydrogels and nanofibrous. This article reviews state-of-the-art gelatin/GelMA-based hybrid scaffolds currently applied for CTE and regenerative therapy. Hybrid scaffolds, fabricated by combining gelatin/GelMA hydrogel or nanofibrous scaffolds with other materials such as natural/synthetic polymers, nanoparticles, protein-based biomaterials, etc., are explored for enhanced cardiac tissue regeneration functionality. The engraftment of stem/cardiac cells, bioactive molecules, or drugs into these hybrid systems shows great promise in cardiac tissue repair and regeneration. Finally, the role of gelatin/GelMA scaffolds combined with the 3D bioprinting strategy in CTE will also be briefly highlighted.

Bibliometric analysis of organoids in regenerative medicine-related research worldwide over two decades (2002-2022)

Aim: This study aimed to evaluate the trends in organoid culture research within the field of regenerative medicine from 2002 to 2022. Methods: The worldwide distribution of organoid research in regenerative medicine articles indexed in the Scopus database was analyzed. Result: A total of 840 documents were analyzed, averaging 42 publications annually. The USA (n = 296) led in publications, followed by China (n = 127), Japan (n = 91) and the UK (n = 75). Since 2011, research has surged, particularly in China, which emerged as a prominent center. Conclusion: The findings highlight significant growth in organoid research, promising future organ transplantation. Research trends integrate tissue engineering, gene modification and induced pluripotent stem cell technologies, reflecting a move toward personalized medicine.

Bioprinting of Cardiac Tissue in Space: Where Are We?

Bioprinting in space is the next frontier in tissue engineering. In the absence of gravity, novel opportunities arise, as well as new challenges. The cardiovascular system needs particular attention in tissue engineering, not only to develop safe countermeasures for astronauts in future deep and long-term space missions, but also to bring solutions to organ transplantation shortage. In this perspective, the challenges encountered when using bioprinting techniques in space and current gaps that need to be overcome are discussed. The recent developments that have been made in the bioprinting of heart tissues in space and an outlook on potential future bioprinting opportunities in space are described.

COVID-19 associated thyroid dysfunction and other comorbidities and its management using phytochemical-based therapeutics: a natural way

The present severe acute respiratory syndrome-2 (SARS-CoV-2) mediated Coronavirus pandemic (COVID-19) and post-COVID-19 complications affect human life drastically. Patients who have been cured of COVID-19 infection are now experiencing post-COVID-19 associated comorbidities, which have increased mortality rates. The SARS-CoV-2 infection distresses the lungs, kidneys, gastrointestinal tract, and various endocrine glands, including the thyroid. The emergence of variants which includes Omicron (B.1.1.529) and its lineages threaten the world severely. Among different therapeutic approaches, phytochemical-based therapeutics are not only cost-effective but also have lesser side effects. Recently a plethora of studies have shown the therapeutic efficacy of various phytochemicals for the treatment of COVID-19. Besides this, various phytochemicals have been found efficacious in treating several inflammatory diseases, including thyroid-related anomalies. The method of the phytochemical formulation is quick and facile and the raw materials for such herbal preparations are approved worldwide for human use against certain disease conditions. Owing to the advantages of phytochemicals, this review primarily discusses the COVID-19-related thyroid dysfunction and the role of key phytochemicals to deal with thyroid anomaly and post-COVID-19 complications. Further, this review shed light on the mechanism via which COVID-19 and its related complication affect organ function of the body, along with the mechanistic insight into the way by which phytochemicals could help to cure post-COVID-19 complications in thyroid patients. Considering the advantages offered by phytochemicals as a safer and cost-effective medication they can be potentially used to combat COVID-19-associated comorbidities.

Cryopreservation: A Comprehensive Overview, Challenges, and Future Perspectives

Cryopreservation is the most prevalent method of long-term cell preservation. Effective cell cryopreservation depends on freezing, adequate storage, and correct thawing techniques. Recent advances in cryopreservation techniques minimize the cellular damage which occurs while processing samples. This article focuses on the fundamentals of cryopreservation techniques and how they can be implemented in a variety of clinical settings. The article presents a brief description of each of the standard cryopreservation procedures, such as slow freezing and vitrification. Alongside that, the membrane permeating and nonpermeating cryoprotectants are briefly discussed, along with current advancements in the field of cryopreservation and variables influencing the cryopreservation process. The diminution of cryoinjury incurred by the cell via the resuscitation process will also be highlighted. In the end application of cryopreservation techniques in many fields, with a special emphasis on stem cell preservation techniques and current advancements presented. Furthermore, the challenges while implementing cryopreservation and the futuristic scope of the fields are illustrated herein. The content of this review sheds light on various ways to enhance the output of the cell preservation process and minimize cryoinjury while improving cell revival.

On the Thermomechanical Behavior of 3D-Printed Specimens of Shape Memory R-PETG

From commercial pellets of recycled polyethylene terephthalate glycol (R-PETG), 1.75 mm diameter filaments for 3D printing were produced. By varying the filament's deposition direction between 10° and 40° to the transversal axis, parallelepiped specimens were fabricated by additive manufacturing. When bent at room temperature (RT), both the filaments and the 3D-printed specimens recovered their shape during heating, either without any constraint or while lifting a load over a certain distance. In this way, free-recovery and work-generating shape memory effects (SMEs) were developed. The former could be repeated without any visible fatigue marks for as much as 20 heating (to 90 °C)-RT cooling-bending cycles, while the latter enabled the lifting of loads over 50 times heavier than the active specimens. Tensile static failure tests revealed the superiority of the specimens printed at larger angles over those printed at 10°, since the specimens printed at 40° had tensile failure stresses and strains over 35 MPa and 8.5%, respectively. Scanning electron microscopy (SEM) fractographs displayed the structure of the successively deposited layers and a shredding tendency enhanced by the increase in the deposition angle. Differential scanning calorimetry (DSC) analysis enabled the identification of the glass transition between 67.5 and 77.3 °C, which might explain the occurrence of SMEs in both the filament and 3D-printed specimens. Dynamic mechanical analysis (DMA) emphasized a local increase in storage modulus of 0.87-1.66 GPa that occurred during heating, which might explain the development of work-generating SME in both filament and 3D-printed specimens. These properties recommend 3D-printed parts made of R-PETG as active elements in low-price lightweight actuators operating between RT and 63 °C.

Development of Three-Dimensional (3D) Biodegradable Polyglycolic Acid Fiber (PGA) Preforms for Scaffold Applications: Experimental Patterning and Fiber Volume Fraction-Porosity Modeling Study

Three-dimensional (3D) biodegradable polyglycolic acid fiber (PGA) preforms were developed as temporary scaffolds for three-dimensional tissue regeneration applications. Three-dimensional biodegradable polyglycolic acid fiber (PGA) preforms including various degrees of interlaced structures called 3D plain, semi-interlaced, and orthogonal woven preforms were designed. Analytical relations and finite element model-based software (TexGen) on fiber volume fraction and porosity fraction were proposed to predict scaffolds' stiffness and strength properties considering micromechanics relations. It was revealed that yarn-to-yarn space, density, and angles of all 3D PGA fiber preforms were heterogeneous and demonstrated direction-dependent features (anisotropy). Total fiber volume fractions (V_fp) and porosity fraction (V_tpr) predicted by analytic and numerical modelling of all 3D scaffolds showed some deviations compared to the measured values. This was because yarn cross-sections in the scaffolds were changed from ideal circular yarn (fiber TOW) geometry to high-order ellipse (lenticular) due to inter-fiber pressure generated under a tensile-based macrostress environment during preform formation. Z-yarn modulus (E_z-yarn) and strength (σ_z-yarn) were probably critical values due to strong stiffness and strength in the through-the-thickness direction where hydrogel modulus and strengths were negligibly small. Morphology of the scaffold showed that PGA fiber sets in the preform were locally distorted, and they appeared as inconsistent and inhomogeneous continuous fiber forms. Additionally, various porosity shapes in the preform based on the virtual model featured complex shapes from nearly trapezoidal beams to partial or concave rectangular beams and ellipsoid rectangular cylinders. It was concluded that 3D polyglycolic acid fiber preforms could be a temporary supportive substrate for 3D tissue regeneration because cells in the scaffold's thickness can grow via through-the-thickness fiber (z-yarn), including various possible mechanobiology mechanisms.

Out of Box Thinking to Tangible Science: A Benchmark History of 3D Bio-Printing in Regenerative Medicine and Tissues Engineering

Advancements and developments in the 3D bioprinting have been promising and have met the needs of organ transplantation. Current improvements in tissue engineering constructs have enhanced their applications in regenerative medicines and other medical fields. The synergistic effects of 3D bioprinting have brought technologies such as tissue engineering, microfluidics, integrated tissue organ printing, in vivo bioprinted tissue implants, artificial intelligence and machine learning approaches together. These have greatly impacted interventions in medical fields, such as medical implants, multi-organ-on-chip models, prosthetics, drug testing tissue constructs and much more. This technological leap has offered promising personalized solutions for patients with chronic diseases, and neurodegenerative disorders, and who have been in severe accidents. This review discussed the various standing printing methods, such as inkjet, extrusion, laser-assisted, digital light processing, and stereolithographic 3D bioprinter models, adopted for tissue constructs. Additionally, the properties of natural, synthetic, cell-laden, dECM-based, short peptides, nanocomposite and bioactive bioinks are briefly discussed. Sequels of several tissue-laden constructs such as skin, bone and cartilage, liver, kidney, smooth muscles, cardiac and neural tissues are briefly analyzed. Challenges, future perspectives and the impact of microfluidics in resolving the limitations in the field, along with 3D bioprinting, are discussed. Certainly, a technology gap still exists in the scaling up, industrialization and commercialization of this technology for the benefit of stakeholders.

High cell density and high-resolution 3D bioprinting for fabricating vascularized tissues

Three-dimensional (3D) bioprinting techniques have emerged as the most popular methods to fabricate 3D-engineered tissues; however, there are challenges in simultaneously satisfying the requirements of high cell density (HCD), high cell viability, and fine fabrication resolution. In particular, bioprinting resolution of digital light processing-based 3D bioprinting suffers with increasing bioink cell density due to light scattering. We developed a novel approach to mitigate this scattering-induced deterioration of bioprinting resolution. The inclusion of iodixanol in the bioink enables a 10-fold reduction in light scattering and a substantial improvement in fabrication resolution for bioinks with an HCD. Fifty-micrometer fabrication resolution was achieved for a bioink with 0.1 billion per milliliter cell density. To showcase the potential application in tissue/organ 3D bioprinting, HCD thick tissues with fine vascular networks were fabricated. The tissues were viable in a perfusion culture system, with endothelialization and angiogenesis observed after 14 days of culture.

Biosensors based detection of novel biomarkers associated with COVID-19: Current progress and future promise

The pandemic situation of COVID-19 has caused global alarm in health care, devastating loss of lives, strangled economy, and paralysis of normal livelihood. The high inter-individual transmission rate created havoc in the global community. Although tremendous efforts are pitching in from across the globe to understand this disease, the clinical features seemed to have a wide range including fever, cough, and fatigue are the prominent features. Congestion, rhinorrhea, sore throat, and diarrhea are other less common features observed. The challenge of this disease lies in the difficulty in maneuvering the clinical course causing severe complications. One of the major causative factors for multi-organ failure in patients with severe COVID-19 complications is systemic vasculitis and cytokine-mediated coagulation disorders. Hence, effective markers trailing the disease severity and disease prognosis are urgently required for prompt medical treatment. In this review article, we have emphasized currently identified inflammatory, hematological, immunological, and biochemical biomarkers of COVID-19. We also discussed currently available biosensors for the detection of COVID-19-associated biomarkers & risk factors and the detection methods as well as their performances. These could be effective tools for rapid and more promising diagnoses in the current pandemic situation. Effective biomarkers and their rapid, scalable, & sensitive detection might be beneficial for the prevention of serious complications and the clinical management of the disease.

Development of Paper Microfluidics with 3D-Printed PDMS Barriers for Flow Control

Paper microfluidics has been extensively exploited as a powerful tool for environmental and medical detection applications. Both flow delay and compatibility with either polar or non-polar reagents are indispensable for the automation of detections requiring multiple reaction steps. This article reports the systematic studies of a 3D-printing protocol, characterization, and application of both the partially and fully penetrated polydimethylsiloxane (PDMS) barriers for flexible flow control in paper microfluidics. The physical parameters of PDMS barriers printed using a simple liquid dispenser were found related to the printing pressure, speed, diffusion time after printing, baking temperature, and PDMS viscosity. The capability of PDMS barriers to confine the flow of non-polar solvents was demonstrated using oil flow in both wax- and PDMS-surrounded channels. It was identified that the minimum width of channels to prevent leakage was 470 ± 54 μm, which was as narrow as that fabricated using stamps from lithography. Both the partially penetrated barriers (PPBs) and constriction channels were of the capability to delay flow in paper microfluidics. Additionally, an in silico investigation led to the further understanding that the reduction of channel cross-section resulting from PPBs was the primary reason for flow delay. Our results suggest that increasing the penetration depth of the barriers is more efficient in delaying flow than increasing the PPB length. Finally, devices with four inlet channels and 0-6 PPBs across each channel were successfully applied in flow delay for sequential fluid delivery. These results improve the understanding of the major factors, affecting the 3D PDMS barrier fabrication and the resulting flow control in paper microfluidics, providing practical implications for applications in various fields.

Microfluidics-Based Point-of-Care Testing (POCT) Devices in Dealing with Waves of COVID-19 Pandemic: The Emerging Solution

Recent advances in microfluidics-based point-of-care testing (POCT) technology such as paper, array, and beads have shown promising results for diagnosing various infectious diseases. The fast and timely detection of viral infection has proven to be a critical step for deciding the therapeutic outcome in the current COVID-19 pandemic, which in turn not only enhances the patient survival rate but also reduces the disease-associated comorbidities. In the present scenario, rapid, noninvasive detection of the virus using low cost and high throughput microfluidics-based POCT devices embraces the advantages over existing diagnostic technologies, for which a centralized lab facility, expensive instruments, sample pretreatment, and skilled personnel are required. Microfluidic-based multiplexed POCT devices can be a boon for clinical diagnosis in developing countries that lacks a centralized health care system and resources. The microfluidic devices can be used for disease diagnosis and exploited for the development and testing of drug efficacy for disease treatment in model systems. The havoc created by the second wave of COVID-19 led several countries' governments to the back front. The lack of diagnostic kits, medical devices, and human resources created a huge demand for a technology that can be remotely operated with single touch and data that can be analyzed on a phone. Recent advancements in information technology and the use of smartphones led to a paradigm shift in the development of diagnostic devices, which can be explored to deal with the current pandemic situation. This review sheds light on various approaches for the development of cost-effective microfluidics POCT devices. The successfully used microfluidic devices for COVID-19 detection under clinical settings along with their pros and cons have been discussed here. Further, the integration of microfluidic devices with smartphones and wireless network systems using the Internet-of-things will enable readers for manufacturing advanced POCT devices for remote disease management in low resource settings.

3D Bioprinting of Novel κ-Carrageenan Bioinks: An Algae-Derived Polysaccharide

Novel green materials not sourced from animals and with low environmental impact are becoming increasingly appealing for biomedical and cellular agriculture applications. Marine biomaterials are a rich source of structurally diverse compounds with various biological activities. Kappa-carrageenan (κ-c) is a potential candidate for tissue engineering applications due to its gelation properties, mechanical strength, and similar structural composition of glycosaminoglycans (GAGs), possessing several advantages when compared to other algae-based materials typically used in bioprinting such as alginate. For those reasons, this material was selected as the main polysaccharide component of the bioinks developed herein. In this work, pristine κ-carrageenan bioinks were successfully formulated for the first time and used to fabricate 3D scaffolds by bioprinting. Ink formulation and printing parameters were optimized, allowing for the manufacturing of complex 3D structures. Mechanical compression tests and dry weight determination revealed young’s modulus between 24.26 and 99.90 kPa and water contents above 97%. Biocompatibility assays, using a mouse fibroblast cell line, showed high cell viability and attachment. The bioprinted cells were spread throughout the scaffolds with cells exhibiting a typical fibroblast-like morphology similar to controls. The 3D bio-/printed structures remained stable under cell culture conditions for up to 11 days, preserving high cell viability values. Overall, we established a strategy to manufacture 3D bio-/printed scaffolds through the formulation of novel bioinks with potential applications in tissue engineering and cellular agriculture.

Balancing the customization and standardization: exploration and layout surrounding the regulation of the growing field of 3D-printed medical devices in China

Medical devices are instruments and other tools that act on the human body to aid clinical diagnosis and disease treatment, playing an indispensable role in modern medicine. Nowadays, the increasing demand for personalized medical devices poses a significant challenge to traditional manufacturing methods. The emerging manufacturing technology of three-dimensional (3D) printing as an alternative has shown exciting applications in the medical field and is an ideal method for manufacturing such personalized medical devices with complex structures. However, the application of this new technology has also brought new risks to medical devices, making 3D-printed devices face severe challenges due to insufficient regulation and the lack of standards to provide guidance to the industry. This review aims to summarize the current regulatory landscape and existing research on the standardization of 3D-printed medical devices in China, and provide ideas to address these challenges. We focus on the aspects concerned by the regulatory authorities in 3D-printed medical devices, highlighting the quality system of such devices, and discuss the guidelines that manufacturers should follow, as well as the current limitations and the feasible path of regulation and standardization work based on this perspective. The key points of the whole process quality control, performance evaluation methods and the concept of whole life cycle management of 3D-printed medical devices are emphasized. Furthermore, the significance of regulation and standardization is pointed out. Finally, aspects worthy of attention and future perspectives in this field are discussed.