Tunable 3D Nanofiber Architecture of Polycaprolactone by Divergence Electrospinning for Potential Tissue Engineering Applications

3D Nanofiber-Assisted Embedded Extrusion Bioprinting for Oriented Cardiac Tissue Fabrication

Three-dimensional (3D) bioprinting technology stands out as a promising tissue manufacturing process to control the geometry precisely with cell-loaded bioinks. However, the isotropic culture environment within the bioink and the lack of topographical cues impede the formation of oriented cardiac tissue. To overcome this limitation, we present a novel method named 3D nanofiber-assisted embedded bioprinting (3D-NFEP) to fabricate cardiac tissue with an oriented morphology. Aligned 3D nanofiber scaffolds were fabricated by divergence electrospinning, which provided structural support for printing of the low-viscosity bioink and structural induction to cardiomyocytes. Cells adhered to the aligned fibers after hydrogel degradation, and a high degree of cell alignment was observed. This technology was also demonstrated as a feasible solution for multilayer cell printing. Therefore, 3D-NFEP was demonstrated as a promising method for bioprinting oriented cardiac tissue with low-viscosity bioink and is expected to be applied for structured and cardiac tissue engineering.

Degradable biomedical elastomers: paving the future of tissue repair and regenerative medicine

Degradable biomedical elastomers (DBE), characterized by controlled biodegradability, excellent biocompatibility, tailored elasticity, and favorable network design and processability, have become indispensable in tissue repair. This review critically examines the recent advances of biodegradable elastomers for tissue repair, focusing mainly on degradation mechanisms and evaluation, synthesis and crosslinking methods, microstructure design, processing techniques, and tissue repair applications. The review explores the material composition and cross-linking methods of elastomers used in tissue repair, addressing chemistry-related challenges and structural design considerations. In addition, this review focuses on the processing methods of two- and three-dimensional structures of elastomers, and systematically discusses the contribution of processing methods such as solvent casting, electrostatic spinning, and three-/four-dimensional printing of DBE. Furthermore, we describe recent advances in tissue repair using DBE, and include advances achieved in regenerating different tissues, including nerves, tendons, muscle, cardiac, and bone, highlighting their efficacy and versatility. The review concludes by discussing the current challenges in material selection, biodegradation, bioactivation, and manufacturing in tissue repair, and suggests future research directions. This concise yet comprehensive analysis aims to provide valuable insights and technical guidance for advances in DBE for tissue engineering.

Microengineering 3D Collagen Matrices with Tumor-Mimetic Gradients in Fiber Alignment

Collagen fibers in the 3D tumor microenvironment (TME) exhibit complex alignment landscapes that are critical in directing cell migration through a process called contact guidance. Previous in vitro work studying this phenomenon has focused on quantifying cell responses in uniformly aligned environments. However, the TME also features short-range gradients in fiber alignment that result from cell-induced traction forces. Although the influence of graded biophysical taxis cues is well established, cell responses to physiological alignment gradients remain largely unexplored. In this work, fiber alignment gradients in biopsy samples are characterized and recreated using a new microfluidic biofabrication technique to achieve tunable sub-millimeter to millimeter scale gradients. This study represents the first successful engineering of continuous alignment gradients in soft, natural biomaterials. Migration experiments on graded alignment show that HUVECs exhibit increased directionality, persistence, and speed compared to uniform and unaligned fiber architectures. Similarly, patterned MDA-MB-231 aggregates exhibit biased migration toward increasing fiber alignment, suggesting a role for alignment gradients as a taxis cue. This user-friendly approach, requiring no specialized equipment, is anticipated to offer new insights into the biophysical cues that cells interpret as they traverse the extracellular matrix, with broad applicability in healthy and diseased tissue environments.

Fabrication of PS/PVDF-HFP Multi-Level Structured Micro/Nano Fiber Membranes by One-Step Electrospinning

Recently, the multi-level interwoven structured micro/nano fiber membranes with coarse and fine overlaps have attracted lots of attention due to their advantages of high surface roughness, high porosity, good mechanical strength, etc., but their simple and direct preparation methods still need to be developed. Herein, the multi-level structured micro/nano fiber membranes were prepared novelly and directly by a one-step electrospinning technique based on the principle of micro-phase separation caused by polymer incompatibility using polystyrene (PS) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) as raw materials. It was found that different spinning fluid parameters and various spinning process parameters will have a significant impact on its morphology and structures. Under certain conditions (the concentration of spinning solution is 18 wt%, the mass ratio of PS to PVDF-HFP is 1:7, the spinning voltage is 30 kV, and the spinning receiving distance is 18 cm), the PS/PVDF-HFP membrane with optimal multi-level structured micro/nano fiber membranes could be obtained, which present an average pore size of 4.38 ± 0.10 μm, a porosity of 78.9 ± 3.5%, and a water contact angle of 145.84 ± 1.70°. The formation mechanism of micro/nano fiber interwoven structures was proposed through conductivity and viscosity tests. In addition, it was initially used as a separation membrane material in membrane distillation, and its performance was preliminarily explored. This paper provides a theoretical and experimental basis for the research and development of an efficient and feasible method for the preparation of multi-level micro/nano fiber membranes.

Cardiac-Adaptive Conductive Hydrogel Patch Enabling Construction of Mechanical-Electrical Anisotropic Microenvironment for Heart Repair

The biomimetic construction of a microstructural-mechanical-electrical anisotropic microenvironment adaptive to the native cardiac tissue is essential to repair myocardial infarction (MI). Inspired by the 3D anisotropic characteristic of the natural fish swim bladder (FSB), a novel flexible, anisotropic, and conductive hydrogel was developed for tissue-specific adaptation to the anisotropic structural, conductive, and mechanical features of the native cardiac extracellular matrix. The results revealed that the originally stiff, homogeneous FSB film was tailored to a highly flexible anisotropic hydrogel, enabling its potential as a functional engineered cardiac patch (ECP). In vitro and in vivo experiments demonstrated the enhanced electrophysiological activity, maturation, elongation, and orientation of cardiomyocytes (CMs), and marked MI repair performance with reduced CM apoptosis and myocardial fibrosis, thereby promoting cell retention, myogenesis, and vascularization, as well as improving electrical integration. Our findings offer a potential strategy for functional ECP and provides a novel strategy to bionically simulate the complex cardiac repair environment.

From 1D Nanofibers to 3D Nanofibrous Aerogels: A Marvellous Evolution of Electrospun SiO2 Nanofibers for Emerging Applications

One-dimensional (1D) SiO2 nanofibers (SNFs), one of the most popular inorganic nanomaterials, have aroused widespread attention because of their excellent chemical stability, as well as unique optical and thermal characteristics. Electrospinning is a straightforward and versatile method to prepare 1D SNFs with programmable structures, manageable dimensions, and modifiable properties, which hold great potential in many cutting-edge applications including aerospace, nanodevice, and energy. In this review, substantial advances in the structural design, controllable synthesis, and multifunctional applications of electrospun SNFs are highlighted. We begin with a brief introduction to the fundamental principles, available raw materials, and typical apparatus of electrospun SNFs. We then discuss the strategies for preparing SNFs with diverse structures in detail, especially stressing the newly emerging three-dimensional SiO2 nanofibrous aerogels. We continue with focus on major breakthroughs about brittleness-to-flexibility transition of SNFs and the means to achieve their mechanical reinforcement. In addition, we showcase recent applications enabled by electrospun SNFs, with particular emphasis on physical protection, health care and water treatment. In the end, we summarize this review and provide some perspectives on the future development direction of electrospun SNFs.

Alginate-Based Composites for Corneal Regeneration: The Optimization of a Biomaterial to Overcome Its Limits

For many years, corneal transplantation has been the first-choice treatment for irreversible damage affecting the anterior part of the eye. However, the low number of cornea donors and cases of graft rejection highlighted the need to replace donor corneas with new biomaterials. Tissue engineering plays a fundamental role in achieving this goal through challenging research into a construct that must reflect all the properties of the cornea that are essential to ensure correct vision. In this review, the anatomy and physiology of the cornea are described to point out the main roles of the corneal layers to be compensated and all the requirements expected from the material to be manufactured. Then, a deep investigation of alginate as a suitable alternative to donor tissue was conducted. Thanks to its adaptability, transparency and low immunogenicity, alginate has emerged as a promising candidate for the realization of bioengineered materials for corneal regeneration. Chemical modifications and the blending of alginate with other functional compounds allow the control of its mechanical, degradation and cell-proliferation features, enabling it to go beyond its limits, improving its functionality in the field of corneal tissue engineering and regenerative medicine.

Rational Design of High-Performance Keratin-Based Hemostatic Agents

Keratins are considered ideal candidates as hemostatic agents, but the development lags far behind their potentials due to the poorly understood hemostatic mechanism and structure-function relations, owing to the composition complexity in protein extracts. Here, it is shown that by using a recombinant synthesis approach, individual types of keratins can be expressed and used for mechanism investigation and further high-performance keratin hemostatic agent design. In the comparative evaluation of full-length, rod-domain, and helical segment keratins, the α-helical contents in the sequences are identified to be directly proportional to keratins' hemostatic activities, and Tyr, Phe, and Gln residues at the N-termini of α-helices in keratins are crucial in fibrinopeptide release and fibrin polymerization. A feasible route to significantly enhance the hemostatic efficiency of helical keratins by mutating Cys to Ser in the sequences for enhanced water wettability through soluble expression is then further presented. These results provide a rational strategy to design high-efficiency keratin hemostatic agents with superior performance over clinically used gelatin sponge in multiple animal models.

A new versatile x-y-z electrospinning equipment for nanofiber synthesis in both far and near field

This work describes a versatile electrospinning equipment with rapid, independent, and precise x–y–z movements for large-area depositions of electrospun fibers, direct writing or assembly of fibers into sub-millimeter and micron-sized patterns, and printing of 3D micro- and nanostructures. Its versatility is demonstrated thought the preparation of multilayered functional nanofibers for wound healing, nanofiber mesh for particle filtration, high-aspect ratio printed lines, and freestanding aligned nanofibers.

Electrospun silk nanofibers promoted the in vitro expansion potential of CD 133+ cells derived from umbilical cord blood

Stem cells from umbilical cord blood (UCB) are able to proliferate and differentiate into various somatic cell types. Thereby, they are considered as one of the attractive stem cell sources in tissue engineering and regenerative medicine. However, the limited number of hematopoietic CD 133⁺ stem cells in UCB restricted the clinical application of such stem cells. This study was aimed to expand CD 133⁺ stem cells derived from UCB on a 3D silk scaffold. UCB133⁺ stem cells were extracted using Magnetic cell sorting (MACS) and characterized by flow cytometry. Isolated cells were seeded on a fabricated electrospun silk scaffold and cultured for 7 days. The real-time PCR, cell counting, colony-forming assay, and MTT assay were performed to evaluate the expansion and homing of stem cells. The results showed a higher expression of CXCR4 gene, the number of cultured stem cells, and colony-forming units in the 3D silk scaffold group after 7 days when compared to the tissue culture plate. Moreover, higher viability and proliferation of stem cells were seen in cells cultured on silk scaffold. It seems electrospun silk scaffold could be used as a suitable substrate for UCB CD 133⁺ stem cell expansion.

High-Porosity Foam-Based Iontronic Pressure Sensor with Superhigh Sensitivity of 9280 kPa-1

Flexible pressure sensors with high sensitivity are desired in the fields of electronic skins, human-machine interfaces, and health monitoring. Employing ionic soft materials with microstructured architectures in the functional layer is an effective way that can enhance the amplitude of capacitance signal due to generated electron double layer and thus improve the sensitivity of capacitive-type pressure sensors. However, the requirement of specific apparatus and the complex fabrication process to build such microstructures lead to high cost and low productivity. Here, we report a simple strategy that uses open-cell polyurethane foams with high porosity as a continuous three-dimensional network skeleton to load with ionic liquid in a one-step soak process, serving as the ionic layer in iontronic pressure sensors. The high porosity (95.4%) of PU-IL composite foam shows a pretty low Young's modulus of 3.4 kPa and good compressibility. A superhigh maximum sensitivity of 9,280 kPa^-1 in the pressure regime and a high pressure resolution of 0.125% are observed in this foam-based pressure sensor. The device also exhibits remarkable mechanical stability over 5,000 compression-release or bending-release cycles. Such high porosity of composite structure provides a simple, cost-effective and scalable way to fabricate super sensitive pressure sensor, which has prominent capability in applications of water wave detection, underwater vibration sensing, and mechanical fault monitoring.

Effects of Viscosities and Solution Composition on Core-Sheath Electrospun Polycaprolactone(PCL) Nanoporous Microtubes

Vascularization for tissue engineering applications has been challenging over the past decades. Numerous efforts have been made to fabricate artificial arteries and veins, while few focused on capillary vascularization. In this paper, core-sheath electrospinning was adopted to fabricate nanoporous microtubes that mimic the native capillaries. The results showed that both solution viscosity and polyethylene oxide (PEO) ratio in polycaprolactone (PCL) sheath solution had significant effects on microtube diameter. Adding PEO into PCL sheath solution is also beneficial to surface pore formation, although the effects of further increasing PEO showed mixed results in different viscosity groups. Our study showed that the high viscosity group with a PCL/PEO ratio of 3:1 resulted in the highest average microtube diameter (2.14 µm) and pore size (250 nm), which mimics the native human capillary size of 1–10 µm. Therefore, our microtubes show high potential in tissue vascularization of engineered scaffolds.

Cell Trapping via Migratory Inhibition within Density-Tuned Electrospun Nanofibers

Cell migration is an essential bioprocess that occurs during wound healing and tissue regeneration. Abnormal cell migration is observed in various pathologies, including cancer metastasis. Glioblastoma multiforme (GBM) is an aggressive and highly infiltrative brain tumor. The white matter tracts are considered the preferred routes for GBM invasion and the subsequent spread throughout the brain tissue. In the present study, a platform based on electrospun nanofibers with a consistent alignment and controlled density was designed to inhibit cell migration. The observation of the cells cultured on the nanofibers with different fiber densities revealed an inverse correlation between the cell migration velocity and nanofiber density. This was attributed to the formation of focal adhesions (FAs). The FAs in the sparse fiber matrix were small, whereas those in the dense fiber matrix were large, aligned with the nanofibers, and distributed throughout the cells. A nanofiber-based platform with stepwise different fiber densities was designed based on the aforementioned observation. A time-lapse observation of the GBM cells cultured on the platform revealed a directional one-way migration that induced the entrapment of cells in the dense-fiber zone. The designed platform mimicked the structure of the white matter tracts and enabled the entrapment of migrating cells. The demonstrated approach is suitable for inhibiting metastasis and understanding the biology of invasion, thereby functioning as a promising therapeutic strategy for GBM.

Milestones and current achievements in development of multifunctional bioscaffolds for medical application

Tissue engineering (TE) is a rapidly growing interdisciplinary field, which aims to restore or improve lost tissue function. Despite that TE was introduced more than 20 years ago, innovative and more sophisticated trends and technologies point to new challenges and development. Current challenges involve the demand for multifunctional bioscaffolds which can stimulate tissue regrowth by biochemical curves, biomimetic patterns, active agents and proper cell types. For those purposes especially promising are carefully chosen primary cells or stem cells due to its high proliferative and differentiation potential. This review summarized a variety of recently reported advanced bioscaffolds which present new functions by combining polymers, nanomaterials, bioactive agents and cells depending on its desired application. In particular necessity of study biomaterial-cell interactions with in vitro cell culture models, and studies using animals with in vivo systems were discuss to permit the analysis of full material biocompatibility. Although these bioscaffolds have shown a significant therapeutic effect in nervous, cardiovascular and muscle, tissue engineering, there are still many remaining unsolved challenges for scaffolds improvement.

Conformal Fabrication of an Electrospun Nanofiber Mat on a 3D Ear Cartilage-Shaped Hydrogel Collector Based on Hydrogel-Assisted Electrospinning

Electrospinning is a common and versatile process to produce nanofibers and deposit them on a collector as a two-dimensional nanofiber mat or a three-dimensional (3D) macroscopic arrangement. However, 3D electroconductive collectors with complex geometries, including protruded, curved, and recessed regions, generally caused hampering of a conformal deposition and incomplete covering of electrospun nanofibers. In this study, we suggested a conformal fabrication of an electrospun nanofiber mat on a 3D ear cartilage-shaped hydrogel collector based on hydrogel-assisted electrospinning. To relieve the influence of the complex geometries, we flattened the protruded parts of the 3D ear cartilage-shaped hydrogel collector by exploiting the flexibility of the hydrogel. We found that the suggested fabrication technique could significantly decrease an unevenly focused electric field, caused by the complex geometries of the 3D collector, by alleviating the standard deviation by more than 70% through numerical simulation. Furthermore, it was experimentally confirmed that an electrospun nanofiber mat conformally covered the flattened hydrogel collector with a uniform thickness, which was not achieved with the original hydrogel collector. Given that this study established the conformal electrospinning technique on 3D electroconductive collectors, it will contribute to various studies related to electrospinning, including tissue engineering, drug/cell delivery, environmental filter, and clothing.

3D Electrospun Nanofiber-Based Scaffolds: From Preparations and Properties to Tissue Regeneration Applications

Electrospun nanofibers have been frequently used for tissue engineering due to their morphological similarities with the extracellular matrix (ECM) and tunable chemical and physical properties for regulating cell behaviors and functions. However, most of the existing electrospun nanofibers have a closely packed two-dimensional (2D) membrane with the intrinsic shortcomings of limited cellular infiltration, restricted nutrition diffusion, and unsatisfied thickness. Three-dimensional (3D) electrospun nanofiber-based scaffolds can provide stem cells with 3D microenvironments and biomimetic fibrous structures. Thus, they have been demonstrated to be good candidates for in vivo repair of different tissues. This review summarizes the recent developments in 3D electrospun nanofiber-based scaffolds (ENF-S) for tissue engineering. Three types of 3D ENF-S fabricated using different approaches classified into electrospun nanofiber 3D scaffolds, electrospun nanofiber/hydrogel composite 3D scaffolds, and electrospun nanofiber/porous matrix composite 3D scaffolds are discussed. New functions for these 3D ENF-S and properties, such as facilitated cell infiltration, 3D fibrous architecture, enhanced mechanical properties, and tunable degradability, meeting the requirements of tissue engineering scaffolds were discovered. The applications of 3D ENF-S in cartilage, bone, tendon, ligament, skeletal muscle, nerve, and cardiac tissue regeneration are then presented with a discussion of current challenges and future directions. Finally, we give summaries and future perspectives of 3D ENF-S in tissue engineering and clinical transformation.

Emerging indocyanine green-integrated nanocarriers for multimodal cancer therapy: a review

Nanotechnology is a branch of science dealing with the development of new types of nanomaterials by several methods. In the biomedical field, nanotechnology is widely used in the form of nanotherapeutics. Therefore, the current biomedical research pays much attention to nanotechnology for the development of efficient cancer treatment. Indocyanine green (ICG) is a near-infrared tricarbocyanine dye approved by the Food and Drug Administration (FDA) for human clinical use. ICG is a biologically safe photosensitizer and it can kill tumor cells by producing singlet oxygen species and photothermal heat upon NIR irradiation. ICG has some limitations such as easy aggregation, rapid aqueous degradation, and a short half-life. To address these limitations, ICG is further formulated with nanoparticles. Therefore, ICG is integrated with organic nanomaterials (polymers, micelles, liposomes, dendrimers and protein), inorganic nanomaterials (magnetic, gold, mesoporous, calcium, and LDH based), and hybrid nanomaterials. The combination of ICG with nanomaterials provides highly efficient therapeutic effects. Nowadays, ICG is used for various biomedical applications, especially in cancer therapeutics. In this review, we mainly focus on ICG-based combined cancer nanotherapeutics for advanced cancer treatment.

Fabrication of Nanopores Polylactic Acid Microtubes by Core-Sheath Electrospinning for Capillary Vascularization

There has been substantial progress in tissue engineering of biological substitutes for medical applications. One of the major challenges in development of complex tissues is the difficulty of creating vascular networks for engineered constructs. The diameter of current artificial vascular channels is usually at millimeter or submillimeter level, while human capillaries are about 5 to 10 µm in diameter. In this paper, a novel core-sheath electrospinning process was adopted to fabricate nanoporous microtubes to mimic the structure of fenestrated capillary vessels. A mixture of polylactic acid (PLA) and polyethylene glycol (PEO) was used as the sheath solution and PEO was used as the core solution. The microtubes were observed under a scanning electron microscope and the images were analyzed by ImageJ. The diameter of the microtubes ranged from 1-8 microns. The diameter of the nanopores ranged from 100 to 800 nm. The statistical analysis showed that the microtube diameter was significantly influenced by the PEO ratio in the sheath solution, pump rate, and the viscosity gradient between the sheath and the core solution. The electrospun microtubes with nanoscale pores highly resemble human fenestrated capillaries. Therefore, the nanoporous microtubes have great potential to support vascularization in engineered tissues.

Hydrogel-Assisted Electrospinning for Fabrication of a 3D Complex Tailored Nanofiber Macrostructure

Electrospinning has shown great potential in tissue engineering and regenerative medicine due to a high surface-area-to-volume ratio and an extracellular matrix-mimicking structure of electrospun nanofibers, but the fabrication of a complex three-dimensional (3D) macroscopic configuration with electrospun nanofibers remains challenging. In the present study, we developed a novel hydrogel-assisted electrospinning process (GelES) to fabricate a 3D nanofiber macrostructure with a 3D complex but tailored configuration by utilizing a 3D hydrogel structure as a grounded collector instead of a metal collector in conventional electrospinning. The 3D hydrogel collector was discovered to effectively concentrate the electric field toward itself similar to the metal collector, thereby depositing electrospun nanofibers directly on its exterior surface. Synergistic advantages of the hydrogel (e.g., biocompatibility and thermally reversible sol-gel transition) and the 3D nanofiber macrostructure (e.g., mechanical robustness and high permeability) provided by the GelES process were demonstrated in a highly permeable tubular tissue graft and a robust drug- or cell-encapsulation construct. GelES is expected to broaden potential applications of electrospinning to not only provide in vivo drug/cell delivery and tissue regeneration but also an in vitro drug testing platform by increasing the degree of freedom in the configuration of the 3D nanofiber macrostructure.

Influence of Controlled Cooling on Crystallinity of Poly (L-Lactic Acid) Scaffolds after Hydrolytic Degradation

The use of hybrid manufacturing to produce bimodal scaffolds has represented a great advancement in tissue engineering. These scaffolds provide a favorable environment in which cells can adhere and produce new tissue. However, there are several areas of opportunity to manufacture structures that provide enough strength and rigidity, while also improving chemical integrity. As an advancement in the manufacturing process of scaffolds, a cooling system was introduced in a fused deposition modeling (FDM) machine to vary the temperature on the printing bed. Two groups of polylactic acid (PLA) scaffolds were then printed at two different bed temperatures. The rate of degradation was evaluated during eight weeks in Hank's Balanced Salt Solution (HBSS) in a controlled environment (37 °C-120 rpm) to assess crystallinity. Results showed the influence of the cooling system on the degradation rate of printed scaffolds after the immersion period. This phenomenon was attributable to the mechanism associated with alkaline hydrolysis, where a higher degree of crystallinity obtained in one group induced greater rates of mass loss. The overall crystallinity was observed, through differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and Fourier transformed infrared spectroscopy (FTIR) analysis, to increase with time because of the erosion of some amorphous parts after immersion.

Fabrication and Plasma Modification of Nanofibrous Tissue Engineering Scaffolds

This paper provides a comprehensive overview of nanofibrous structures for tissue engineering purposes and the role of non-thermal plasma technology (NTP) within this field. Special attention is first given to nanofiber fabrication strategies, including thermally-induced phase separation, molecular self-assembly, and electrospinning, highlighting their strengths, weaknesses, and potentials. The review then continues to discuss the biodegradable polyesters typically employed for nanofiber fabrication, while the primary focus lies on their applicability and limitations. From thereon, the reader is introduced to the concept of NTP and its application in plasma-assisted surface modification of nanofibrous scaffolds. The final part of the review discusses the available literature on NTP-modified nanofibers looking at the impact of plasma activation and polymerization treatments on nanofiber wettability, surface chemistry, cell adhesion/proliferation and protein grafting. As such, this review provides a complete introduction into NTP-modified nanofibers, while aiming to address the current unexplored potentials left within the field.

Yttrium oxide nanoparticle loaded scaffolds with enhanced cell adhesion and vascularization for tissue engineering applications

In situ tissue engineering is emerging as a novel approach in tissue engineering to repair damaged tissues by boosting the natural ability of the body to heal itself. This can be achieved by providing suitable signals and scaffolds that can augment cell migration, cell adhesion on the scaffolds and proliferation of endogenous cells that facilitate the repair. Lack of appropriate cell proliferation and angiogenesis are among the major issues associated with the limited success of in situ tissue engineering during in vivo studies. Exploitation of metal oxide nanoparticles such as yttrium oxide (Y₂O₃) nanoparticles may open new horizons in in situ tissue engineering by providing cues that facilitate cell proliferation and angiogenesis in the scaffolds. In this context, Y₂O₃ nanoparticles were synthesized and incorporated in polycaprolactone (PCL) scaffolds to enhance the cell proliferation and angiogenic properties. An optimum amount of Y₂O₃-containing scaffolds (1% w/w) promoted the proliferation of fibroblasts (L-929) and osteoblast-like cells (UMR-106). Results of chorioallantoic membrane (CAM) assay and the subcutaneous implantation studies in rats demonstrated the angiogenic potential of the scaffolds loaded with Y₂O₃ nanoparticles. Gene expression study demonstrated that the presence of Y₂O₃ in the scaffolds can upregulate the expression of cell proliferation and angiogenesis related biomolecules such as VEGF and EGFR. Obtained results demonstrated that Y₂O₃ nanoparticles can perform a vital role in tissue engineering scaffolds to promote cell proliferation and angiogenesis.