3D-printed polycaprolactone scaffolds coated with beta tricalcium phosphate for bone regeneration.

BACKGROUND/PURPOSE: 3D-printing technology is an important tool for the bone tissue engineering (BTE). The aim of this study was to investigate the interaction of polycaprolactone (PCL) scaffolds and modified mesh PCL coated with beta TCP (PCL/ß-TCP) scaffolds with MG-63. METHODS: This study used the fused deposition modeling (FDM) technique with the 3D printing technique to fabricate the thermoplastic polymer and composite scaffolds. Scaffold structure and coating quality were observed under a scanning electron microscope (SEM). MG-63 cells were injected and attached to the mesh-manufactured PCL scaffolds. The biocompatibility of mesh structured PCL and PCL/ß-TCP scaffolds could be examined by measuring the viability of MG-63 cells of MTT assay. Bone cell differentiation was evaluated ALP activity by mineralization assay. RESULTS: The results showed that both mesh PCL scaffolds and PCL/ß-TCP scaffolds were non-toxic to the cells. The ALP activities of cells in PCL/ß-TCP scaffolds groups were significant differences and better than PCL groups in all groups at all experimental dates. The mineralization process was time-dependent, and significantly higher mineralization of osteosarcoma cells was observed on PCL/ß-TCP scaffolds at experimental dates. CONCLUSION: We concluded that both meshes structured PCL and PCL/ß-TCP scaffolds could promote the MG-63 cell growth, and PCL/ß-TCP was better than the PCL scaffolds for the outcome of MG63 cell differentiation and mineralization.

Bladder Regeneration Using a Polycaprolactone Scaffold with a Gradient Structure and Growth Factors in a Partially Cystectomized Rat Model.

BACKGROUND: Tissue engineering can be used for bladder augmentation. However, conventional scaffolds result in fibrosis and graft shrinkage. This study applied an alternative polycaprolactone (PCL)-based scaffold (diameter = 5 mm) with a noble gradient structure and growth factors (GFs) (epidermal growth factor, vascular endothelial growth factor, and basic fibroblast growth factor) to enhance bladder tissue regeneration in a rat model. METHODS: Partially excised urinary bladders of 5-week-old male Slc:SD rats were reconstructed with the scaffold (scaffold group) or the scaffold combined with GFs (GF group) and compared with sham-operated (control group) and untreated rats (partial cystectomy group). Evaluations of bladder volume, histology, immunohistochemistry (IHC), and molecular markers were performed at 4, 8, and 12 weeks after operation. RESULTS: The bladder volumes of the scaffold and GF group recovered to the normal range, and those of the GF group showed more enhanced augmentation. Histological evaluations revealed that the GF group showed more organized urothelial lining, dense extracellular matrix, frequent angiogenesis, and enhanced smooth muscle bundle regeneration than the scaffold group. IHC for α-smooth muscle actin, pan-cytokeratin, α-bungarotoxin, and CD8 revealed that the GF group showed high formation of smooth muscle, blood vessel, urothelium, neuromuscular junction and low immunogenicity. Concordantly, real-time polymerase chain reaction experiments revealed that the GF group showed a higher expression of transcripts associated with smooth muscle and urothelial differentiation. In a 6-month in vivo safety analysis, the GF group showed normal histology. CONCLUSION: This study showed that a PCL scaffold with a gradient structure incorporating GFs improved bladder regeneration functionally and histologically.

Vascular restoration through local delivery of angiogenic factors stimulates bone regeneration in critical size defects.

Critical size bone defects represent a significant challenge worldwide, often leading to persistent pain and physical disability that profoundly impact patients' quality of life and mental well-being. To address the intricate and complex repair processes involved in these defects, we performed single-cell RNA sequencing and revealed notable shifts in cellular populations within regenerative tissue. Specifically, we observed a decrease in progenitor lineage cells and endothelial cells, coupled with an increase in fibrotic lineage cells and pro-inflammatory cells within regenerative tissue. Furthermore, our analysis of differentially expressed genes and associated signaling pathway at the single-cell level highlighted impaired angiogenesis as a central pathway in critical size bone defects, notably influenced by reduction of Spp1 and Cxcl12 expression. This deficiency was particularly pronounced in progenitor lineage cells and myeloid lineage cells, underscoring its significance in the regeneration process. In response to these findings, we developed an innovative approach to enhance bone regeneration in critical size bone defects. Our fabrication process involves the integration of electrospun PCL fibers with electrosprayed PLGA microspheres carrying Spp1 and Cxcl12. This design allows for the gradual release of Spp1 and Cxcl12 in vitro and in vivo. To evaluate the efficacy of our approach, we locally applied PCL scaffolds loaded with Spp1 and Cxcl12 in a murine model of critical size bone defects. Our results demonstrated restored angiogenesis, accelerated bone regeneration, alleviated pain responses and improved mobility in treated mice.

Polycaprolactone-based scaffolds for guided tissue regeneration in periodontal therapy: A systematic review.

BACKGROUND: Polycaprolactone (PCL) is a highly recognized synthetic polymer for its biocompatibility, ease of fabrication and mechanical strength in bone tissue engineering. Its applications have extended broadly, including regeneration of oral and maxillofacial lost tissues. Its usefulness has brought attention of researchers to regenerate periodontal lost tissues, including alveolar bone, periodontal ligament and cementum. The aim of this systematic review was to obtain an updated analysis of the contribution of PCL-based scaffolds in the alveolar bone regeneration process. METHODS: This review adheres to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for systematic reviews. A computerized search of the PubMed, EBSCO, Scielo and Web of Science databases was performed, restricting literature search to published studies in English or Spanish between January 2002 and March 2023. Database search returned 248 studies which were screened based on title, author names and publication dates. RESULTS: Data from 17 studies were reviewed and tabulated. All studies combined PCL with other biomaterials (such as Alginate, hydroxyapatite, bioactive glass, poly (lactic-co-glycolic acid)), growth factors (BMP-2, rhCEMP1), and/or mesenchymal stromal cells (adipose-derived, bone marrow, periodontal ligament or gingiva mesenchymal stromal cells). PCL scaffolds showed higher cell viability and osteoinductive potential when combined with bioactive agents. Complementary, its degradation rates were affected by the addition or exposure to specific substances, such as: Dopamine, Cerium Oxide, PLGA and hydrogen peroxide. CONCLUSIONS: PCL is an effective biomaterial for alveolar bone regeneration in periodontally affected teeth. It could be part of a new generation of biomaterials with improved regenerative potential.

Effect of porosity on mechanical and biological properties of bioprinted scaffolds.

Treatment of tissue defects commonly represents a major problem in clinics due to difficulties involving a shortage of donors, inappropriate sizes, abnormal shapes, and immunological rejection. While many scaffold parameters such as pore shape, porosity percentage, and pore connectivity could be adjusted to achieve desired mechanical and biological properties. These parameters are crucial scaffold parameters that can be accurately produced by 3D bioprinting technology based on the damaged tissue. In the present research, the effect of porosity percentage (40%, 50%, and 60%) and different pore shapes (square, star, and gyroid) on the mechanical (e.g., stiffness, compressive and tensile behavior) and biological (e.g., biodegradation, and cell viability) properties of porous polycaprolactone (PCL) scaffolds coated with gelatin have been investigated. Moreover, human foreskin fibroblast cells were cultured on the scaffolds in the in-vitro procedures. MTT assay (4, 7, and 14 days) was utilized to determine the cytotoxicity of the porous scaffolds. It is revealed that the porous scaffolds produced by the bioprinter did not produce a cytotoxic effect. Among all the porous scaffolds, scaffolds with a pore size of about 500 µm and porosity of 50% showed the best cell proliferation compared to the controls after 14 days. The results demonstrated that the pore shape, porosity percentage, and pore connectivity have an important role in improving the mechanical and biological properties of porous scaffolds. These 3D bioprinted biodegradable scaffolds exhibit potential for future application as polymeric scaffolds in hard tissue engineering applications.

Skin 11ß-hydroxysteroid dehydrogenase type 1 enzyme expression regulates burn wound healing and can be targeted to modify scar characteristics.

Background: Excessive scarring and fibrosis are the most severe and common complications of burn injury. Prolonged exposure to high levels of glucocorticoids detrimentally impacts on skin, leading to skin thinning and impaired wound healing. Skin can generate active glucocorticoids locally through expression and activity of the 11ß-hydroxysteroid dehydrogenase type 1 enzyme (11ß-HSD1). We hypothesised that burn injury would induce 11ß-HSD1 expression and local glucocorticoid metabolism, which would have important impacts on wound healing, fibrosis and scarring. We additionally proposed that pharmacological manipulation of this system could improve aspects of post-burn scarring. Methods: Skin 11ß-HSD1 expression in burns patients and mice was examined. The impacts of 11ß-HSD1 mediating glucocorticoid metabolism on burn wound healing, scar formation and scar elasticity and quality were additionally examined using a murine 11ß-HSD1 genetic knockout model. Slow-release scaffolds containing therapeutic agents, including active and inactive glucocorticoids, were developed and pre-clinically tested in mice with burn injury. Results: We demonstrate that 11ß-HSD1 expression levels increased substantially in both human and mouse skin after burn injury. 11ß-HSD1 knockout mice experienced faster wound healing than wild type mice but the healed wounds manifested significantly more collagen deposition, tensile strength and stiffness, features characteristic of excessive scarring. Application of slow-release prednisone, an inactive glucocorticoid, slowed the initial rate of wound closure but significantly reduced post-burn scarring via reductions in inflammation, myofibroblast generation, collagen production and scar stiffness. Conclusions: Skin 11ß-HSD1 expression is a key regulator of wound healing and scarring after burn injury. Application of an inactive glucocorticoid capable of activation by local 11ß-HSD1 in skin slows the initial rate of wound closure but significantlyimproves scar characteristics post burn injury.

Outcome Analysis of Osseous Ingrowth in an Artificially Created Gap Non-union Using the Novel 3D Biodegradable Polycaprolactone Poly-l-Lactide Polymer Scaffold: Insights from an Experimental Study.

Background: Synthetic biopolymers have been widely used to manage bone effects in recent years. The study aims to analyse the ability to repair artificially created ulnar bone defects with the scaffold made of Polycaprolactone (PCL) and investigate the material's feasibility as a bone graft substitute. Method: We have tested a novel 3D biodegradable Polycaprolactone Poly-l-Lactide polymer scaffold in an experimental animal model. 14 adults New Zealand white rabbits were used to create the ulnar defect model of 10 mm in length, and randomly divided into group A (test-12 rabbits), group B (control-3 rabbits). The defect area was implanted with the PCL scaffold in the test group, whereas it was left as such in the control group. The repairing effect was observed by gross, histology, radiology, and the Scanning electron microscopy (SEM) at 4, 8, and 12 weeks. Cook's scoring was used to assess the radiological parameters. Results: Histological and radiological results showed better quality of bone regeneration in the defect area at 12 week follow-up period. The SEM image at that period showed impregnation of the osteogenic cells in the surface and pores of the scaffold material. It was evident that the scaffold was thoroughly degraded, corresponding with osteogenesis. New bone formation was statistically significant in the test group than in the control group. Conclusion: The Polycaprolactone Poly-l-Lactide polymer scaffold is biodegradable in-vivo at a suitable half-life. It has an excellent porous structure, no tissue toxicity, excellent mechanical strength, high osteogenesis potential, and osteoconductivity. Therefore, it can be used as bone graft material in the gap non-union and as a void filler in bone defects.

Current Applications of Polycaprolactone as a Scaffold Material for Heart Regeneration.

Despite numerous advances in treatments for cardiovascular disease, heart failure (HF) remains the leading cause of death worldwide. A significant factor contributing to the progression of cardiovascular diseases into HF is the loss of functioning cardiomyocytes. The recent growth in the field of cardiac tissue engineering has the potential to not only reduce the downstream effects of injured tissues on heart function and longevity but also re-engineer cardiac function through regeneration of contractile tissue. One leading strategy to accomplish this is via a cellularized patch that can be surgically implanted onto a diseased heart. A key area of this field is the use of tissue scaffolds to recapitulate the mechanical and structural environment of the native heart and thus promote engineered myocardium contractility and function. While the strong mechanical properties and anisotropic structural organization of the native heart can be largely attributed to a robust extracellular matrix, similar strength and organization has proven to be difficult to achieve in cultured tissues. Polycaprolactone (PCL) is an emerging contender to fill these gaps in fabricating scaffolds that mimic the mechanics and structure of the native heart. In the field of cardiovascular engineering, PCL has recently begun to be studied as a scaffold for regenerating the myocardium due to its facile fabrication, desirable mechanical, chemical, and biocompatible properties, and perhaps most importantly, biodegradability, which make it suitable for regenerating and re-engineering function to the heart after disease or injury. This review focuses on the application of PCL as a scaffold specifically in myocardium repair and regeneration and outlines current fabrication approaches, properties, and possibilities of PCL incorporation into engineered myocardium, as well as provides suggestions for future directions and a roadmap toward clinical translation of this technology.

Surface Modification of Polycaprolactone Scaffold With Improved Biocompatibility and Controlled Growth Factor Release for Enhanced Stem Cell Differentiation.

Polycaprolactone (PCL) has been widely used as a scaffold material for tissue engineering. Reliable applications of the PCL scaffolds require overcoming their native hydrophobicity and obtaining the sustained release of signaling factors to modulate cell growth and differentiation. Here, we report a surface modification strategy for electrospun PCL nanofibers using an azide-terminated amphiphilic graft polymer. With multiple alkylation and pegylation on the side chains of poly-L-lysine, stable coating of the graft polymer on the PCL nanofibers was achieved in one step. Using the azide-alkyne "click chemistry", we functionalized the azide-pegylated PCL nanofibers with dibenzocyclooctyne-modified nanocapsules containing growth factor, which rendered the nanofiber scaffold with satisfied cell adhesion and growth property. Moreover, by specific immobilization of pH-responsive nanocapsules containing bone morphogenetic protein 2 (BMP-2), controlled release of active BMP-2 from the PCL nanofibers was achieved within 21 days. When bone mesenchyme stem cells were cultured on this nanofiber scaffold, enhanced ossification was observed in correlation with the time-dependent release of BMP-2. The established surface modification can be extended as a generic approach to hydrophobic nanomaterials for longtime sustainable release of multiplex signaling proteins for tissue engineering.

Effect of 3D printed polycaprolactone scaffold with a bionic structure on the early stage of fat grafting.

Mature adipocytes are sensitive to stress and hypoxia, which are the two major obstacles in large-volume fat grafting. Bionic scaffolds are considered beneficial for fat grafting; however, their mechanism is still unclear. In this study, polycaprolactone scaffolds were fabricated by a 3D-printing technique and compounded with liposuction fat. They were implanted subcutaneously into nude mice. At different times, gross and histological observations were performed to evaluate the retention rates and histological morphologies. Adipocyte viability, apoptosis, and vascularization were analyzed by special immunostaining. Quantitative polymerase chain reaction was used to detect the variations in hypoxia and inflammation. The results showed that the volume and weight retentions in the scaffold group were higher than those in the fat group with the former exhibiting fewer vacuoles and less fibrosis. In immunostaining, elevated CD31+ capillaries, more perilipin+ adipocytes, and fewer TUNEL+ apoptotic cells were observed in the scaffold group by week 4. The lower expression of HIF-1α indicated the alleviation of hypoxia. In conclusion, the scaffold provided mechanical support to resist skin tension, thereby decreasing the interstitial pressure, and improving substance exchange and vascular ingrowth. In this regard, the scaffold attenuated hypoxia and promoted vascularization, making it a feasible method to increase long-term retention in fat grafting using scaffolds with suitable degradation rates and additional vascular maturation stimulation.

Preparing polycaprolactone scaffolds using electrospinning technique for construction of artificial periodontal ligament tissue.

OBJECTIVES: The strategies of tissue-engineering led to the development of living cell-based therapies to repair lost or damaged tissues, including periodontal ligament and to construct biohybrid implant. This work aimed to isolate human periodontal ligament stem cells (hPDLSCs) and implant them on fabricated polycaprolactone (PCL) for the regeneration of natural periodontal ligament (PDL) tissues. METHODS: hPDLSCs were harvested from extracted human premolars, cultured, and expanded to obtain PDL cells. A PDL-specific marker (periostin) was detected using an immunofluorescent assay. Electrospinning was applied to fabricate PCL at three concentrations (13%, 16%, and 20% weight/volume) in two forms, which were examined through field emission scanning electron microscopy (FESEM). The isolated hPDLSCs were implanted on the fabricated PCL. After 21 days, FESEM was conducted to evaluate the implanted scaffolds, and an MTT assay was performed to characterize the biological response of the PCL scaffold at different cell exposure durations (24, 48, and 72 h). RESULTS: Periostin was expressed in the expanded PDL cells, and this result revealed that 20% weight/volume PCL scaffold with a pore size of more than 10 µm was the best. The growth rates of PDLSCs were high. Cytotoxicity test of fabricated PCL scaffold demonstrated no significant change in the cell viability when compared with the negative control and no deteriorating or inhibitory effect on growth after different durations. CONCLUSIONS: A cell sheet was successfully formed by using PCL as a scaffold to cover dental implants and promote PDL cell attachment, proliferation, and growth for biohybrid implant construction.

Evaluation of polycaprolactone scaffold for guided bone regeneration in maxillary and mandibular defects: A clinical study.

OBJECTIVE: This study was carried out to assess bone regeneration following the use of polycaprolactone (PCL) scaffold in maxillary and mandibular osseous defects. MATERIALS AND METHODS: This prospective study included ten patients with maxillary or mandibular osseous defects present due to enucleation of periapical cysts or alveolar clefts requiring bone grafting and for lateral ridge augmentation that were treated with PCL scaffold. The patients were assessed clinically for pain, swelling, infection, and graft exposure at 1 week, 3rd, and 5th month postoperatively and were also evaluated radiographically for bone fill using intraoral periapical and/or panoramic radiographs at 4th, 6th, and 9th month postoperatively. RESULTS: PCL scaffold was used in a total of six alveolar clefts and three cases of periapical cysts and one case of lateral ridge augmentation. Nine out of ten cases demonstrated wound dehiscence and scaffold exposure in the oral cavity. Radiographically, on comparison to the control regions, all these nine cases failed to demonstrate appreciable bone density gain. Only one case of radicular cyst in the mandible was recorded to have satisfactory healing. CONCLUSION: Although PCL scaffold has the potential for bone regeneration in osseous defects, the scaffold exhibited marked tendency for dehiscence in intraoral defects that significantly affected bone healing. A long-term study designed with a larger sample size and categorization of the defects is required to assess its efficacy in varied defects. Moreover, comparative evaluation of PCL and autogenous or alloplastic bone grafting material could provide assenting results.

Tubular open-porous ß-tricalcium phosphate polycaprolactone scaffolds as guiding structure for segmental bone defect regeneration in a novel sheep model.

Large segmental bone defect reconstruction with sufficient functional restoration is one of the most demanding challenges in orthopaedic surgery. Available regenerative treatment options, as the vascularized bone graft transfer, the Masquelet technique or the Ilizarov distraction osteogenesis, are associated with specific indications and distinct limitations. As an alternative, a hollow cylindrical ceramic-polymer composite scaffold (ß-tricalcium phosphate and poly-lactid co-ε- caprolactone), facilitating a strong surface guiding effect for tissue ingrowth (group 1; n = 6) was investigated here. In combination with an additional autologous, cancellous bone graft filling, the scaffold's ability to work as an open-porous membrane to improve the defect healing process was analysed (group 2; n = 6). A novel model of a critical size (40 mm) tibia osteotomy defect stabilized with an external hybrid-ring fixator, was established in sheep. Segmental defect regeneration and tissue organization in relation to the scaffold were analysed radiologically, (immune-) histologically, and with second-harmonic generation imaging 12 weeks after surgery. The scaffold's tubular shape and open-porous structure controlled the collagen fibre orientation within the bone defect and guided the following mineralization process along the scaffold surface. In combination with the osteoinductive stimulus, a unilateral bony bridging of the critically sized defect was achieved in one third of the animals. The external hybrid-ring fixator was appropriate for large segmental defect stabilization in sheep.

3D Printed, PVA⁻PAA Hydrogel Loaded-Polycaprolactone Scaffold for the Delivery of Hydrophilic In-Situ Formed Sodium Indomethacin.

3D printed polycaprolactone (PCL)-blended scaffolds have been designed, prepared, and evaluated in vitro in this study prior to the incorporation of a polyvinyl alcohol⁻polyacrylic acid (PVA⁻PAA) hydrogel for the delivery of in situ-formed sodium indomethacin. The prepared PCL⁻PVA⁻PAA scaffold is proposed as a potential structural support system for load-bearing tissue damage where inflammation is prevalent. Uniaxial strain testing of the PCL-blended scaffolds were undertaken to determine the scaffold’s resistance to strain in addition to its thermal, structural, and porosimetric properties. The viscoelastic properties of the incorporated PVA⁻PAA hydrogel has also been determined, as well as the drug release profile of the PCL⁻PVA⁻PAA scaffold. Results of these analyses noted the structural strength, thermal stability, and porosimetric properties of the scaffold, as well as the ability of the PCL⁻PVA⁻PAA scaffold to deliver sodium indomethacin in simulated physiological conditions of pH and temperature. The results of this study therefore highlight the successful design, fabrication, and in vitro evaluation of a 3D printed polymeric strain-resistant supportive platform for the delivery of sodium indomethacin.

Tracheal suspension by using 3-dimensional printed personalized scaffold in a patient with tracheomalacia.

The major methods are used to fix or stabilize the central airways and major bronchi with either anterior suspension and/or posterior fixation for severe tracheomalacia (TM). Many support biomaterials, like mesh and sternal plate, can be used in the surgery. But there are no specialized biomaterials for TM which must be casually fabricated by the doctors in operation. Three dimensional printing (3DP) has currently untapped potential to provide custom, protean devices for challenging and life-threatening disease processes. After meticulous design, we created a polycaprolactone (PCL) scaffold for a female patient with TM, which would support for at least 24 months, to maintain the native lumen size of collapsed airways. Using 4-0 Polyglactin sutures, we grasped and suspended the malacic trachea into the scaffold. A remarkable improvement can be observed in the view of bronchoscope and chest CT after surgery. In the narrowest cavity of malacic trachea, the inner diameter increased from 0.3 to 1.0 cm, and the cross sectional area increased 4-5 times. The patient felt an obvious relief of dyspnea after surgery. In a word, the 3DP PCL scaffold can supply a personalized tool for suspending the malacic trachea in the future.

Electrical stimulation of adipose-derived mesenchymal stem cells in conductive scaffolds and the roles of voltage-gated ion channels.

Since electrical stimulation (ES) can significantly accelerate bone healing, a conductive scaffold that can deliver ES locally at the defect site is desirable for bone defect therapy. Herein, an electrically conductive scaffold was prepared via incorporation of polypyrrole (PPY) in a polycaprolactone (PCL) template scaffold. In vitro tests with mouse osteoblasts indicate that the PPY/PCL scaffold has good biocompatibility, and is suitable for use as an ES substrate. When human adipose-derived mesenchymal stem cells (AD-MSCs) were cultured in the PPY/PCL scaffold and subjected to 200 µA of direct current for 4h per day for 21 days, the amount of calcium deposited was 100% higher than that without ES. When these cells were subjected to ES together with blockers of voltage-gated calcium (Ca(2+)v), sodium (Na(+)v), potassium (K(+)v), or chloride (Cl(-)v) channels, the ES-induced enhancement of AD-MSCs' functions was reduced with Na(+)v, K(+)v, or Cl(-)v blockers and completely nullified with Ca(2+)v blocker. These results indicate that ion fluxes through these channels activated by ES induce different cascades of reactions in the cells, which subsequently regulate AD-MSCs' functions, and Ca(2+)v plays a more critical role than the other three channels. Our results further the current understanding of the mechanisms by which ES regulates stem cells' behavior, and also showed that the conductive PPY/PCL scaffold with application of ES has good potential in bone defect therapy. STATEMENT OF SIGNIFICANCE: In this work, an electrically conductive and biocompatible scaffold was prepared by incorporating polypyrrole in a polycaprolactone template scaffold. Application of 200 µA direct current for 4h per day to human adipose derived-mesenchymal stem cells cultured on this scaffold promoted migration of these cells into the inner region of the scaffold and enhanced their osteogenic differentiation. The roles of voltage-gated ion channels (Ca(2+)v, Na(+)v, K(+)v and Cl(-)v) in osteogenic differentiation stimulated by the electric current were investigated. The results from these experiments further the current understanding of the mechanisms by which electrical stimulation regulates stem cells' behavior, and also show that the polypyrrole-polycaprolactone scaffold with application of electrical stimulation has good potential in bone defect therapy.

The inter-sample structural variability of regular tissue-engineered scaffolds significantly affects the micromechanical local cell environment.

Rapid prototyping techniques have been widely used in tissue engineering to fabricate scaffolds with controlled architecture. Despite the ability of these techniques to fabricate regular structures, the consistency with which these regular structures are produced throughout the scaffold and from one scaffold to another needs to be quantified. Small variations at the pore level can affect the local mechanical stimuli sensed by the cells thereby affecting the final tissue properties. Most studies assume rapid prototyping scaffolds as regular structures without quantifying the local mechanical stimuli at the cell level. In this study, a computational method using a micro-computed tomography-based scaffold geometry was developed to characterize the mechanical stimuli within a real scaffold at the pore level. Five samples from a commercial polycaprolactone scaffold were analysed and computational fluid dynamics analyses were created to compare local velocity and shear stress values at the same scaffold location. The five samples did not replicate the computer-aided design (CAD) scaffold and velocity and shear stress values were up to five times higher than the ones calculated in the CAD scaffold. In addition high variability among samples was found: at the same location velocity and shear stress values could be up to two times higher from sample to sample. This study shows that regular scaffolds need to be thoroughly analysed in order to quantify real cell mechanical stimuli so inspection methods should be included as part of the fabrication process.