Extrusion 3D Printing of Porous Silicone Architectures for Engineering Human Cardiomyocyte-Infused Patches Mimicking Adult Heart Stiffness

Harnessing 3D Printing and Electrospinning for Multiscale Hybrid Patches Mimicking the Native Myocardium

Engineered cardiac tissues show potential for regenerative therapy in ischemic heart disease. Yet, selection of soft biomaterials for scaffold manufacturing is primarily influenced by empirical and compositional factors, raising concerns about arrhythmic risks due to poor electrophysiological integration. Addressing this, we developed multiscale hybrid myocardial patches mimicking native myocardium's structural and biomechanical attributes, utilizing 3D printing and electrospinning techniques. We compared three patch types: pure silicone and silicone-poly(lactic-co-glycolic acid) (PLGA) with random (S-PLGA-R) and aligned (S-PLGA-A) fibers. S-PLGA-A patches with fiber orientation angles of 95-115° are achieved by applying a secondary electrical field using two parallel aluminum enhancers. With bulk and localized moduli of 350-750 and 13-20 kPa resembling the native myocardium, S-PLGA-A patches demonstrate a sarcomere length of 2.1 ± 0.2 μm, ≥50% higher strain motions and diastolic phase, and a 50-70% slower rise of calcium handling compared to the other two patches. This enhanced maturation and improved synchronization phenomena are attributed to efficient force transmission and reduced stress concentration due to mechanical similarity and linear propagation of electrical signals. This study presents a promising strategy for advancing regenerative cardiac therapies by harnessing the capabilities of 3D printing and electrospinning, providing a proof-of-concept for their effectiveness.

3D printing stretchable and compressible porous structures by polymerizable emulsions for soft robotics

UV-curable 3D printing compositions for the fabrication of stretchable and flexible porous structures for soft robotics are presented. The stereolithography-based printing compositions are water-in-oil (W/O) emulsions in which water droplets are the pore-forming material, and the continuous phase is a stretchable polyurethane diacrylate (PUA). The porosity of the printed objects is controlled by the material's micro-porosity and by the macro-porosity obtained by a cellular design. The mechanical behavior can be tailored by the composition of the emulsion, providing both compliance and strength while utilizing a unique optimization methodology for fitting the ink to the 3D printer. This approach enables developing materials having superior mechanical properties, with the highest reported elongation-at-break for 3D printed porous structures, 450%. The emulsion-based printing compositions were utilized for fabricating a soft robotic gripper with unique actuation performance that could not be obtained with commonly used materials.

Novel Osteochondral Biotemplate Improves Long-term Cartilage Repair Compared With Microfracture in an Ovine Model

BACKGROUND

Current cartilage repair therapies do not re-create the complex mechanical interface between cartilage and bone, which is critical for long-term repair durability. New biomaterial designs that include hard tissue-soft tissue interface structures offer promise to improve clinical outcomes.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate the efficacy and safety of a naturally derived osteochondral biotemplate with a novel contiguous hard tissue-soft tissue interface in an ovine model as a regenerative solution for articular cartilage defects. It was hypothesized that the osteochondral biotemplate would produce structurally superior repair tissue compared with microfracture over a 13-month period.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteochondral biotemplates were manufactured from porcine cancellous bone. Skeletally mature sheep (N = 30) were randomly allocated to 3 groups: early healing stage (euthanasia at 4 months), 6-month treatment, and 13-month treatment. In the early healing stage group, an 8 mm-diameter by 5 mm-deep osteochondral defect was created on the medial femoral condyle and treated at the time of iatrogenic injury with an osteochondral biotemplate. The contralateral limb received the same treatment 2 months later. In the 6- and 13-month treatment groups, 1 limb received the same osteochondral procedure as the early healing stage group. In the contralateral limb, an 8 mm-diameter, full-thickness cartilage defect (1-2 mm deep) was created and treated with microfracture. Cartilage repair and integration were quantitatively and qualitatively assessed with gross inspection, histological evaluation, and magnetic resonance imaging (MRI). Wilcoxon signed-rank and McNemar tests were used to compare the treatments.

RESULTS

At 6 and 13 months after treatment, the biotemplate was not present histologically. At 13 months, the biotemplate treatment demonstrated statistically higher histological scores than microfracture for integration with surrounding cartilage (biotemplate: 74 ± 31; microfracture: 28 ± 39; P = .03), type 2 collagen (biotemplate: 72 ± 33; microfracture: 40 ± 38; P = .02), total cartilage (biotemplate: 71 ± 9; microfracture: 59 ± 9; P = .01), and total integration (biotemplate: 85 ± 15; microfracture: 66 ± 20; P = .04). The osteochondral biotemplate treatment produced a notable transient nonneutrophilic inflammatory response that appeared to approach resolution at 13 months. MRI results were not statistically different between the 2 treatments.

CONCLUSION

Even with the inflammatory response, after 13 months, the osteochondral biotemplate outperformed microfracture in cartilage regeneration and demonstrated superiority in integration between the repair tissue and host tissue as well as integration between the newly formed cartilage and the underlying bone.

CLINICAL RELEVANCE

This work has demonstrated the clinical potential of a novel biomaterial template to regenerate the complex mechanical interface between cartilage and the subchondral bone.

3D printing of cell-delivery scaffolds for tissue regeneration

Tissue engineering strategy that combine biomaterials with living cells has shown special advantages in tissue regeneration and promoted the development of regenerative medicine. In particular, the rising of 3D printing technology further enriched the structural design and composition of tissue engineering scaffolds, which also provided convenience for cell loading and cell delivery of living cells. In this review, two types of cell-delivery scaffolds for tissue regeneration, including 3D printed scaffolds with subsequent cell-seeding and 3D cells bioprinted scaffolds, are mainly reviewed. We devote a major part to present and discuss the recent advances of two 3D printed cell-delivery scaffolds in regeneration of various tissues, involving bone, cartilage, skin tissues etc. Although two types of 3D printed cell-delivery scaffolds have some shortcomings, they do have generally facilitated the exploration of tissue engineering scaffolds in multiple tissue regeneration. It is expected that 3D printed cell-delivery scaffolds will be further explored in function mechanism of seeding cells in vivo, precise mimicking of complex tissues and even organ reconstruction under the cooperation of multiple fields in future.

4D Printing Applications in the Development of Smart Cardiovascular Implants

Smart materials are able to react to different stimuli and adapt their shape to the environment. Although the development of 3D printing technology increased the reproducibility and accuracy of scaffold fabrication, 3D printed scaffolds can still be further improved to resemble the native anatomy. 4D printing is an innovative fabrication approach combining 3D printing and smart materials, also known as stimuli-responsive materials. Especially for cardiovascular implants, 4D printing can promisingly create programmable, adaptable prostheses, which facilitates implantation and/or create the topology of the target tissue post implantation. In this review, the principles of 4D printing with a focus on the applied stimuli are explained and the underlying 3D printing technologies are presented. Then, according to the type of stimulus, recent applications of 4D printing in constructing smart cardiovascular implants and future perspectives are discussed.