bims-biprem 2024-05-19 papers

bims-biprem

Biomed News

on Bioprinting for regenerative medicine

Issue of 2024‒05‒19
fourteen papers selected by
Seerat Maqsood, University of Teramo

Three-Dimensional Bioprinting: The Ultimate Pinnacle of Tissue Engineering.
Confined bioprinting and culture in inflatable bioreactor for the sterile bioproduction of tissues and organs.
Application of 3D Printing in Cleft Lip and Palate Repair.
A xenogeneic extracellular matrix-based 3D printing scaffold modified by ceria nanoparticles for craniomaxillofacial hard tissue regeneration via osteo-immunomodulation.
Development and Characterization of Heparin-Containing Hydrogel/3D-Printed Scaffold Composites for Craniofacial Reconstruction.
3D Printing and Development of Optimized and Accurate, Personalized Surgical Plans for Complex Pelvic and Acetabular Fractures.
Enhanced hyaline cartilage formation and continuous osteochondral regeneration via 3D-Printed heterogeneous hydrogel with multi-crosslinking inks.
Innovative technologies for the fabrication of 3D/4D smart hydrogels and its biomedical applications - A comprehensive review.
Effect of 3D-printed polycaprolactone/osteolectin scaffolds on the odontogenic differentiation of human dental pulp cells.
Granular Biphasic Colloidal Hydrogels for 3D Bioprinting.
Evaluating osteogenic potential of a 3D-printed bioceramic-based scaffold for critical-sized defect treatment: an in vivo and in vitro investigation.
Creating 3D constructs with cranial neural crest-derived cell lines using a bio-3D printer.
3D printed VEGF-CPO biomaterial scaffold to promote subcutaneous vascularization and survival of transplanted islets for the treatment of diabetes.
4D hydrogels: fabrication strategies, stimulation mechanisms, and biomedical applications.

Cureus. 2024 Apr;16(4): e58029

Three-Dimensional Bioprinting: The Ultimate Pinnacle of Tissue Engineering.

Parkavi Arumugam, G Kaarthikeyan, Rajalakshmanan Eswaramoorthy.

  Three-dimensional (3D) bioprinting has emerged as a revolutionary additive manufacturing technology that can potentially enable life-changing medical treatments in regenerative medicine. It applies the principles of tissue engineering for the printing of tissues and organs in a layer-by-layer manner. This review focuses on the various 3D bioprinting technologies currently available, the different biomaterials, cells, and growth factors that can be utilized to develop tissue-specific bioinks, the different venues for applying these technologies, and the challenges this technology faces.

Keywords:  bioink; extrusion-based bioprinting; growth factors; stem cells; three-dimensional bioprinting; tissue regeneration

DOI:  https://doi.org/10.7759/cureus.58029
Sci Rep. 2024 05 14. 14(1): 11003

Confined bioprinting and culture in inflatable bioreactor for the sterile bioproduction of tissues and organs.

Alexandre Dufour, Lucie Essayan, Céline Thomann, Emma Petiot, Isabelle Gay, Magali Barbaroux, Christophe Marquette.

  The future of organ and tissue biofabrication strongly relies on 3D bioprinting technologies. However, maintaining sterility remains a critical issue regardless of the technology used. This challenge becomes even more pronounced when the volume of bioprinted objects approaches organ dimensions. Here, we introduce a novel device called the Flexible Unique Generator Unit (FUGU), which is a unique combination of flexible silicone membranes and solid components made of stainless steel. Alternatively, the solid components can also be made of 3D printed medical-grade polycarbonate. The FUGU is designed to support micro-extrusion needle insertion and removal, internal volume adjustment, and fluid management. The FUGU was assessed in various environments, ranging from custom-built basic cartesian to sophisticated 6-axis robotic arm bioprinters, demonstrating its compatibility, flexibility, and universality across different bioprinting platforms. Sterility assays conducted under various infection scenarios highlight the FUGU's ability to physically protect the internal volume against contaminations, thereby ensuring the integrity of the bioprinted constructs. The FUGU also enabled bioprinting and cultivation of a 14.5 cm3 human colorectal cancer tissue model within a completely confined and sterile environment, while allowing for the exchange of gases with the external environment. This FUGU system represents a significant advancement in 3D bioprinting and biofabrication, paving the path toward the sterile production of implantable tissues and organs.

Keywords:  Bioprinting; Bioreactor; Confined environment; Organs production

DOI:  https://doi.org/10.1038/s41598-024-60382-2
J Craniofac Surg. 2024 May 13.

Application of 3D Printing in Cleft Lip and Palate Repair.

Sophie S Kelly, Camila A Suarez, Nicholas A Mirsky, Blaire V Slavin, Baylee Brochu, Vasudev Vivekanand Nayak, Muhammad El Shatanofy, Lukasz Witek, Seth R Thaller, Paulo G Coelho.

This manuscript reviews the transformative impact of 3-dimensional (3D) printing technologies in the treatment and management of cleft lip and palate (CLP), highlighting its application across presurgical planning, surgical training, implantable scaffolds, and postoperative care. By integrating patient-specific data through computer-aided design and manufacturing, 3D printing offers tailored solutions that improve surgical outcomes, reduce operation times, and enhance patient care. The review synthesizes current research findings, technical advancements, and clinical applications, illustrating the potential of 3D printing to revolutionize CLP treatment. Further, it discusses the future directions of combining 3D printing with other innovative technologies like artificial intelligence, 4D printing, and in situ bioprinting for more comprehensive care strategies. This paper underscores the necessity for multidisciplinary collaboration and further research to overcome existing challenges and fully utilize the capabilities of 3D printing in CLP repair.

DOI: https://doi.org/10.1097/SCS.0000000000010294
Biomed Mater. 2024 May 17. 19(4):

A xenogeneic extracellular matrix-based 3D printing scaffold modified by ceria nanoparticles for craniomaxillofacial hard tissue regeneration via osteo-immunomodulation.

Jiahao Chen, Yibing Huang, Huilin Tang, Xiangchen Qiao, Xiutian Sima, Weihua Guo.

  Hard tissue engineering scaffolds especially 3D printed scaffolds were considered an excellent strategy for craniomaxillofacial hard tissue regeneration, involving crania and facial bones and teeth. Porcine treated dentin matrix (pTDM) as xenogeneic extracellular matrix has the potential to promote the stem cell differentiation and mineralization as it contains plenty of bioactive factors similar with human-derived dentin tissue. However, its application might be impeded by the foreign body response induced by the damage-associated molecular patterns of pTDM, which would cause strong inflammation and hinder the regeneration. Ceria nanoparticles (CNPs) show a great promise at protecting tissue from oxidative stress and influence the macrophages polarization. Using 3D-bioprinting technology, we fabricated a xenogeneic hard tissue scaffold based on pTDM xenogeneic TDM-polycaprolactone (xTDM/PCL) and we modified the scaffolds by CNPs (xTDM/PCL/CNPs). Through series ofin vitroverification, we found xTDM/PCL/CNPs scaffolds held promise at up-regulating the expression of osteogenesis and odontogenesis related genes including collagen type 1, Runt-related transcription factor 2 (RUNX2), bone morphogenetic protein-2, osteoprotegerin, alkaline phosphatase (ALP) and DMP1 and inducing macrophages to polarize to M2 phenotype. Regeneration of bone tissues was further evaluated in rats by conducting the models of mandibular and skull bone defects. Thein vivoevaluation showed that xTDM/PCL/CNPs scaffolds could promote the bone tissue regeneration by up-regulating the expression of osteogenic genes involving ALP, RUNX2 and bone sialoprotein 2 and macrophage polarization into M2. Regeneration of teeth evaluated on beagles demonstrated that xTDM/PCL/CNPs scaffolds expedited the calcification inside the scaffolds and helped form periodontal ligament-like tissues surrounding the scaffolds.

Keywords:  3D-bioprinting; ceria nanoparticles; hard tissue regeneration; immunomodulation; xenogeneic extracellular matrix

DOI:  https://doi.org/10.1088/1748-605X/ad475c
Ann Biomed Eng. 2024 May 11.

Development and Characterization of Heparin-Containing Hydrogel/3D-Printed Scaffold Composites for Craniofacial Reconstruction.

Nettie E Brown, Lela R Ellerbe, Scott J Hollister, Johnna S Temenoff.

  Regeneration of cartilage and bone tissues remains challenging in tissue engineering due to their complex structures, and the need for both mechanical support and delivery of biological repair stimuli. Therefore, the goal of this study was to develop a composite scaffold platform for anatomic chondral and osteochondral repair using heparin-based hydrogels to deliver small molecules within 3D-printed porous scaffolds that provide structure, stiffness, and controlled biologic delivery. We designed a mold-injection system to combine hydrolytically degradable hydrogels and 3D-printed scaffolds that could be employed rapidly (< 30 min) in operating room settings (~23 °C). Micro-CT analysis demonstrated the effectiveness of our injection system through homogeneously distributed hydrogel within the pores of the scaffolds. Hydrogels and composite scaffolds exhibited efficient loading (~94%) of a small positively charged heparin-binding molecule (crystal violet) with sustained release over 14 days and showed high viability of encapsulated porcine chondrocytes over 7 days. Compression testing demonstrated nonlinear viscoelastic behavior where tangent stiffness decreased with scaffold porosity (porous scaffold tangent stiffness: 70%: 4.9 MPa, 80%: 1.5 MPa, and 90%: 0.20 MPa) but relaxation was not affected. Lower-porosity scaffolds (70%) showed stiffness similar to lower ranges of trabecular bone (4-8 MPa) while higher-porosity scaffolds (80% and 90%) showed stiffness similar to auricular cartilage (0.16-2 MPa). Ultimately, this rapid composite scaffold fabrication method may be employed in the operating room and utilized to control biologic delivery within load-bearing scaffolds.

Keywords:  3D printing; Composite scaffolds; Finite element analysis; Hydrogels; Tissue engineering

DOI:  https://doi.org/10.1007/s10439-024-03530-z
Altern Ther Health Med. 2024 May 10. pii: AT10002. [Epub ahead of print]

3D Printing and Development of Optimized and Accurate, Personalized Surgical Plans for Complex Pelvic and Acetabular Fractures.

Minglu Wang, Huasong Luo, Wei Chu, Mohamed Lamin Bangura.

Context: Multiple high-energy injuries and complex, pelvic acetabular fractures are challenging injuries. With the help of a 1:1-sized solid model of the human body, 3D printing technology can achieve personalized customization of the surgical methods.Objective: The study intended to compare the clinical efficacy of three-dimensional (3D)-printing-assisted and traditional, open reduction and internal fixation in the treatment of complex pelvic acetabular fractures.
Design: The research team conducted a randomized controlled trial and also provided a case study for one participant in the intervention group.
Setting: The study took place at the First Affiliated Hospital of Yangtze University in Jingzhou, Hubei, China.
Participants: Participants were 48 patients with complex pelvic acetabular fractures at the hospital between January and December 2018.
Interventions: The research team randomly divided participants into two groups, with 24 participants in each group: (1) the 3D group, which received treatment in which surgeons used 3D-printing technology for preoperative planning, and (2) the routine group, which received routine treatment.
Outcome Measures: The research team measured: (1) perioperative conditions, including operation time, intraoperative blood loss, and postoperative drainage volume; (2) fracture reduction quality; and (3) a case study of a postoperative imaging examination.
Results: The 3D group's operation time (P = .001), intraoperative blood loss (P = .001), and postoperative drainage volume (P = .001) were significantly lower than those of routine group. According to the Matta imaging standards, the fracture reduction quality for the 3D group was excellent for 16 participants (66.66%), good for four participants (16.67%), and fair for four participants (16.67%), with the total quality rate at 83.33% for 20 participants. For the routine group, the quality was excellent for eight participants (33.33%), good for four participants (16.67%), and fair for 12 participants (50.00%), with the excellent and good rates at 50.00% for 12 participants. The 3D group's fracture reduction quality was significantly higher than that of the routine group (P < .05).
Conclusions: 3D printing technology in the treatment of complex pelvic acetabular fractures can be helpful for surgeons to understand a fracture's characteristics; formulate an optimized and accurate, personalized surgical plan before an operation; improve the reduction's safety and accuracy; shorten the operation time; reduce the occurrence of postoperative complications; and improve clinical efficacy.
Mater Today Bio. 2024 Jun;26 101080

Enhanced hyaline cartilage formation and continuous osteochondral regeneration via 3D-Printed heterogeneous hydrogel with multi-crosslinking inks.

Zhonglian Wu, Hang Yao, Haidi Sun, Zehao Gu, Xu Hu, Jian Yang, Junli Shi, Haojun Yang, Jihang Dai, Hui Chong, Dong-An Wang, Liwei Lin, Wang Zhang.

  The unique gradient structure and complex composition of osteochondral tissue pose significant challenges in defect regeneration. Restoration of tissue heterogeneity while maintaining hyaline cartilage components has been a difficulty of an osteochondral tissue graft. A novel class of multi-crosslinked polysaccharide-based three-dimensional (3D) printing inks, including decellularized natural cartilage (dNC) and nano-hydroxyapatite, was designed to create a gradient scaffold with a robust interface-binding force. Herein, we report combining a dual-nozzle cross-printing technology and a gradient crosslinking method to create the scaffolds, demonstrating stable mechanical properties and heterogeneous bilayer structures. Biofunctional assessments revealed the remarkable regenerative effects of the scaffold, manifesting three orders of magnitude of mRNA upregulation during chondrogenesis and the formation of pure hyaline cartilage. Transcriptomics of the regeneration site in vivo and scaffold cell interaction tests in vitro showed that printed porous multilayer scaffolds could form the correct tissue structure for cell migration. More importantly, polysaccharides with dNC provided a hydrophilic microenvironment. The microenvironment is crucial in osteochondral regeneration because it could guide the regenerated cartilage to ensure the hyaline phenotype.

Keywords:  3D printing; Bionic hydrogel; Gradient crosslinking; Hyaline cartilage; osteochondral repair

DOI:  https://doi.org/10.1016/j.mtbio.2024.101080
Adv Colloid Interface Sci. 2024 May 07. pii: S0001-8686(24)00086-1. [Epub ahead of print]328 103163

Innovative technologies for the fabrication of 3D/4D smart hydrogels and its biomedical applications - A comprehensive review.

Uday Shashikumar, Aditya Saraswat, Kalim Deshmukh, Chaudhery Mustansar Hussain, Pranjal Chandra, Pei-Chien Tsai, Po-Chin Huang, Yi-Hsun Chen, Liang-Yin Ke, Yuan-Chung Lin, Shashi Chawla, Vinoth Kumar Ponnusamy.

  Repairing and regenerating damaged tissues or organs, and restoring their functioning has been the ultimate aim of medical innovations. 'Reviving healthcare' blends tissue engineering with alternative techniques such as hydrogels, which have emerged as vital tools in modern medicine. Additive manufacturing (AM) is a practical manufacturing revolution that uses building strategies like molding as a viable solution for precise hydrogel manufacturing. Recent advances in this technology have led to the successful manufacturing of hydrogels with enhanced reproducibility, accuracy, precision, and ease of fabrication. Hydrogels continue to metamorphose as the vital compatible bio-ink matrix for AM. AM hydrogels have paved the way for complex 3D/4D hydrogels that can be loaded with drugs or cells. Bio-mimicking 3D cell cultures designed via hydrogel-based AM is a groundbreaking in-vivo assessment tool in biomedical trials. This brief review focuses on preparations and applications of additively manufactured hydrogels in the biomedical spectrum, such as targeted drug delivery, 3D-cell culture, numerous regenerative strategies, biosensing, bioprinting, and cancer therapies. Prevalent AM techniques like extrusion, inkjet, digital light processing, and stereo-lithography have been explored with their setup and methodology to yield functional hydrogels. The perspectives, limitations, and the possible prospects of AM hydrogels have been critically examined in this study.

Keywords:  3D/4D printing; Biosensors; Digital light processing (DLP); Stereolithography (SLD); Targeted drug delivery; Tissue engineering; cancer therapy

DOI:  https://doi.org/10.1016/j.cis.2024.103163
Biomed Mater. 2024 May 13.

Effect of 3D-printed polycaprolactone/osteolectin scaffolds on the odontogenic differentiation of human dental pulp cells.

Kkot-Byeol Bae, Hae-Mi Kim, Ji-Won Son, Jae-Young Ryu, Yun-Chan Hwang, Jeong-Tae Koh, Wonmann Oh, Chan Park, Bin-Na Lee.

  Cell-based tissue engineering often requires the use of scaffolds to provide a 3-dimensional (3D) framework for cell proliferation and tissue formation. Polycaprolactone (PCL), a type of polymer, has good printability, favorable surface modifiability, adaptability, and biodegradability. However, its large-scale applicability is hindered by its hydrophobic nature, which affects biological properties. Composite materials can be created by adding bioactive materials to the polymer to improve the properties of PCL scaffolds (PSs). Osteolectin is an odontogenic factor that promotes the maintenance of the adult skeleton by promoting the differentiation of LepR+ cells into osteoblasts. Therefore, the aim of this study was to evaluate whether 3D-printed PCL/osteolectin scaffolds supply a suitable microenvironment for the odontogenic differentiation of human dental pulp cells (hDPCs). The hDPCs were cultured on 3D-printed PSs with or without pores. Cell attachment and cell proliferation were evaluated using EZ-Cytox. The odontogenic differentiation of hDPCs was evaluated by alizarin red S staining and alkaline phosphatase assays. Western blotting was used to evaluate the expression of the proteins DSPP and DMP-Results: The attachment of hDPCs to PSs with pores was significantly higher than to PSs without pores. The odontogenic differentiation of hDPCs was induced more in PCL/osteolectin scaffolds than in PSs, but there was no statistically significant difference. 3D-printed PSs with pores are suitable for the growth of hDPCs, and the PCL/osteolectin scaffolds can provide a more favorable microenvironment for the odontogenic differentiation of hDPCs.&#xD.

Keywords:  3D-printed polycaprolactone; human dental pulp cell; odontogenic differentiation; osteolectin

DOI:  https://doi.org/10.1088/1748-605X/ad4ad9
Adv Healthc Mater. 2024 May 15. e2303810

Granular Biphasic Colloidal Hydrogels for 3D Bioprinting.

Kaivalya A Deo, Aparna Murali, James J Tronolone, Cole Mandrona, Hung Pang Lee, Satyam Rajput, Sarah Hargett, Amirali Selahi, Yuxiang Sun, Daniel Alge, Abhishek Jain, Akhilesh K Gaharwar.

  Granular hydrogels composed of hydrogel microparticles are promising candidates for 3D bioprinting due to their ability to protect encapsulated cells. However, to achieve high print fidelity, hydrogel microparticles need to jam to exhibit shear-thinning characteristics, which is crucial for 3D printing. Unfortunately, this overpacking can significantly impact cell viability, thereby negating the primary advantage of using hydrogel microparticles to shield cells from shear forces. To overcome this challenge, we introduce a novel solution: a biphasic, granular colloidal bioink designed to optimize cell viability and printing fidelity. The biphasic ink consists of cell-laden polyethylene glycol (PEG) hydrogel microparticles embedded in a continuous gelatin methacryloyl (GelMA)-nanosilicate colloidal network. Here, we demonstrate that this biphasic bioink offers outstanding rheological properties, print fidelity, and structural stability. Furthermore, we demonstrate its utility for engineering complex tissues with multiple cell types and heterogeneous microenvironments, which we demonstrate by incorporating β-islet cells into the PEG microparticles and endothelial cells in the GelMA-nanosilicate colloidal network. Using this approach, it is possible to induce cell patterning, enhance vascularization, and direct cellular function. The proposed biphasic bioink holds significant potential for numerous emerging biomedical applications, including tissue engineering and disease modeling. This article is protected by copyright. All rights reserved.

Keywords:  3D bioprinting; Hydrogel microparticles; drug delivery; granular colloidal hydrogels; nanocomposite

DOI:  https://doi.org/10.1002/adhm.202303810
In Vitro Cell Dev Biol Anim. 2024 May 14.

Evaluating osteogenic potential of a 3D-printed bioceramic-based scaffold for critical-sized defect treatment: an in vivo and in vitro investigation.

Hannaneh Safiaghdam, Sahar Baniameri, Hossein Aminianfar, Saeed Farzad Mohajeri, Mohammad Mehdi Dehghan, Lobat Tayebi, Hanieh Nokhbatolfoghahaei, Arash Khojasteh.

  The integration of precision medicine principles into bone tissue engineering has ignited a wave of research focused on customizing intricate scaffolds through advanced 3D printing techniques. Bioceramics, known for their exceptional biocompatibility and osteoconductivity, have emerged as a promising material in this field. This article aims to evaluate the regenerative capabilities of a composite scaffold composed of 3D-printed gelatin combined with hydroxyapatite/tricalcium phosphate bioceramics (G/HA/TCP), incorporating human dental pulp-derived stem cells (hDPSCs). Using 3D powder printing, we created cross-shaped biphasic calcium phosphate scaffolds with a gelatin layer. The bone-regenerating potential of these scaffolds, along with hDPSCs, was assessed through in vitro analyses and in vivo studies with 60 rats and critical-sized calvarial defects. The assessment included analyzing cellular proliferation, differentiation, and alkaline phosphatase activity (ALP), and concluded with a detailed histological evaluation of bone regeneration. Our study revealed a highly favorable scenario, displaying not only desirable cellular attachment and proliferation on the scaffolds but also a notable enhancement in the ALP activity of hDPSCs, underscoring their pivotal role in bone regeneration. However, the histological examination of calvarial defects at the 12-wk mark yielded a rather modest level of bone regeneration across all experimental groups. The test and cell group exhibited significant bone formation compared to all other groups except the control and cell group. This underscores the complexity of the regenerative process and paves the way for further in-depth investigations aimed at improving the potential of the composite scaffolds.

Keywords:  3D printing; Bioceramic; Bone scaffold; Bone tissue engineering; Rat calvarial defect

DOI:  https://doi.org/10.1007/s11626-024-00912-4
J Oral Biosci. 2024 May 13. pii: S1349-0079(24)00088-4. [Epub ahead of print]

Creating 3D constructs with cranial neural crest-derived cell lines using a bio-3D printer.

Masahide Taguchi, Shohei Yoshimoto, Kanako Suyama, Satoko Sumi, Shirabe Ohki, Kayoko Ogata, Ryota Fujimoto, Daiki Murata, Koichi Nakayama, Kyoko Oka.

  OBJECTIVES: The development of bio-three-dimensional (bio-3D) printers has led to significant advances in regenerative medicine. Three-dimensional constructs, including spheroids, are maintained by extracellular matrix proteins secreted by cells so that the cells can be cultured in conditions closer to the physiological environment. This study aimed to create a useful 3D construct as a model of the dentin-pulp complex METHODS: We examined the expression patterns of extracellular matrix proteins and cell proliferation areas in a 3D construct created using O9-1 cells derived from cranial neural crest cells of mice. The 3D construct was created by sticking the spheroid cultures onto a needle array using a bio-3D printer.RESULTS: Cell proliferation areas along with characteristic expression of tenascin C and DMP1 were evaluated. The expression of tenascin C and DMP1 was significantly enhanced in the spheroids compared to that in two-dimensional cultures. Moreover, cell proliferation regions and tenascin C expression were confirmed in the outer layer of spheroids in the embryonic stem cell medium, with insignificant DMP1 expression being observed. Interestingly, in a 3D construct cultured in calcification-induction medium, DMP1 expression was promoted, and DMP1-positive cells existed in the outermost layer without overlapping with tenascin C expression.
CONCLUSIONS: The extracellular matrix proteins, tenascin C and DMP1, were expressed in a polarized manner in spheroids and 3D constructs, similar to the findings in the dental papilla. Therefore, these 3D constructs show potential as artificial models for studying odontogenesis.

Keywords:  3D constructs; bio-3D printer; spheroid; tenascin C

DOI:  https://doi.org/10.1016/j.job.2024.05.005
Int J Biol Macromol. 2024 May 13. pii: S0141-8130(24)03181-7. [Epub ahead of print] 132376

3D printed VEGF-CPO biomaterial scaffold to promote subcutaneous vascularization and survival of transplanted islets for the treatment of diabetes.

Xuchun Chen, Kangchun Wang, Yang Han, Qi Pan, Xinrui Jiang, Zitong Yu, Weichen Zhang, Ziqi Wang, Haomin Yan, Ping Sun, Jingjing Liang, Heran Li, Ying Cheng.

  Diabetes is a complex metabolic disease and islet transplantation is a promising approach for the treatment of diabetes. Unfortunately, the transplanted islets at the subcutaneous site are also affected by various adverse factors such as poor vascularization and hypoxia. In this study, we utilize biocompatible copolymers l-lactide and D,l-lactide to manufacture a biomaterial scaffold with a mesh-like structure via 3D printing technology, providing a material foundation for encapsulating pancreatic islet cells. The scaffold maintains the sustained release of vascular endothelial growth factor (VEGF) and a slow release of oxygen from calcium peroxide (CPO), thereby regulating the microenvironment for islet survival. This helps to improve insufficient subcutaneous vascularization and reduce islet death due to hypoxia post-transplantation. By pre-implanting VEGF-CPO scaffolds subcutaneously into diabetic rats, a sufficiently vascularized site is formed, thereby ensuring early survival of transplanted islets. In a word, the VEGF-CPO scaffold shows good biocompatibility both in vitro and in vivo, avoids the adverse effects on the implanted islets, and displays promising clinical transformation prospects.

Keywords:  3D printing; Diabetes; Islet transplantation; Oxygen; Vascular endothelial growth factor

DOI:  https://doi.org/10.1016/j.ijbiomac.2024.132376
Biomater Sci. 2024 May 14.

4D hydrogels: fabrication strategies, stimulation mechanisms, and biomedical applications.

Amit Nain, Srishti Chakraborty, Nipun Jain, Saswat Choudhury, Suravi Chattopadhyay, Kaushik Chatterjee, Souvik Debnath.

Shape-morphing hydrogels have emerged as a promising biomaterial due to their ability to mimic the anisotropic tissue composition by creating a gradient in local swelling behavior. In this case, shape deformations occur due to the non-uniform distribution of internal stresses, asymmetrical swelling, and shrinking of different parts of the same hydrogel. Herein, we discuss the four-dimensional (4D) fabrication techniques (extrusion-based printing, dynamic light processing, and solvent casting) employed to prepare shape-shifting hydrogels. The important distinction between mono- and dual-component hydrogel systems, the capabilities of 3D constructs to undergo uni- and bi-directional shape changes, and the advantages of composite hydrogels compared to their pristine counterparts are presented. Subsequently, various types of actuators such as moisture, light, temperature, pH, and magnetic field and their role in achieving the desired and pre-determined shapes are discussed. These 4D gels have shown remarkable potential as programmable scaffolds for tissue regeneration and drug-delivery systems. Finally, we present futuristic insights into integrating piezoelectric biopolymers and sensors to harvest mechanical energy from motions during shape transformations to develop self-powered biodevices.

DOI: https://doi.org/10.1039/d3bm02044d