The Use of Poly-d,l-lactic Acid (PDLLA) Devices for Bone Augmentation Techniques: A Systematic Review

Highly Cytocompatible Polylactic Acid Based Electrospun Microfibers Loaded with Silver Nanoparticles Generated onto Chestnut Shell Lignin for Targeted Antibacterial Activity and Antioxidant Action

Electrospun (e-spun) fibers are generally regarded as powerful tools for cell growth in tissue regeneration applications, and the possibility of imparting functional properties to these materials represents an increasingly pursued goal. We report herein the preparation of hybrid materials in which an e-spun d,l-polylactic acid matrix, to which chitosan or crystalline nanocellulose was added to improve hydrophilicity, was loaded with different amounts of silver(0) nanoparticles (AgNP) generated onto chestnut shell lignin (CSL) (AgNP@CSL). A solvent-free mechanochemical method was used for efficient (85% of the theoretical value by XRD analysis) Ag(0) production from the reduction of AgNO3 by lignin. For comparison, e-spun fibers containing CSL alone were also prepared. SEM and TEM analyses confirmed the presence of AgNP@CSL (average size 30 nm) on the fibers. Different chemical assays indicated that the AgNP@CSL containing fibers exhibited marked antioxidant properties (EC50 1.6 ± 0.1 mg/mL, DPPH assay), although they were halved with respect to those of the CSL containing fibers, as expected because of the efficient silver ion reduction. All the fibers showed high cytocompatibility toward human mesenchymal stem cells (hMSCs) representative of the self-healing process, and their antibacterial properties were tested against the pathogens Escherichia coli (E. coli), Staphylococcus epidermidis, and Pseudomonas aeruginosa. Finally, competitive surface colonization as simulated by cocultures of hMSC and E. coli showed that AgNP@CSL loaded fibers offered the cells a targeted protection from infection, thus well balancing cytocompatibility and antibacterial properties.

Effect of Gelatin Content on Degradation Behavior of PLLA/Gelatin Hybrid Membranes

BACKGROUND

Poly(L-lactic acid) (PLLA) is a biodegradable polymer (BP) that replaces conventional petroleum-based polymers.  The hydrophobicity of biodegradable PLLA periodontal barrier membrane in wet state can be solved by alloying it with natural polymers. Alloying PLLA with gelatin imparts wet mechanical properties, hydrophilicity, shrinkage, degradability and biocompatibility to the polymeric matrix.

METHODS

To investigate membrane performance in the wet state, PLLA/gelatin membranes were synthesized by varying the gelatin concentration from 0 to 80 wt%. The membrane was prepared by electrospinning.

RESULTS

At the macroscopic scale, PLLA containing gelatin can tune the wet mechanical properties, hydrophilicity, water uptake capacity (WUC), degradability and biocompatibility of PLLA/gelatin membranes. As the gelatin content increased from 0 to 80 wt%, the dry tensile strength of the membranes increased from 6.4 to 38.9 MPa and the dry strain at break decreased from 1.7 to 0.19. PLLA/gelatin membranes with a gelatin content exceeding 40% showed excellent biocompatibility and hydrophilicity. However, dimensional change (37.5% after 7 days of soaking), poor tensile stress  in wet state (3.48 MPa) and rapid degradation rate (73.7%) were observed. The highest WUC, hydrophilicity, porosity, suitable mechanical properties and biocompatibility were observed for the PLLA/40% gelatin membrane.

CONCLUSION

PLLA/gelatin membranes with gelatin content less than 40% are suitable as barrier membranes for absorbable periodontal tissue regeneration due to their tunable wet mechanical properties, degradability, biocompatibility and lack of dimensional changes.

Gelatin Enhances the Wet Mechanical Properties of Poly(D,L-Lactic Acid) Membranes

Biodegradable (BP) poly(D,L-lactic acid) (PDLLA) membranes are widely used in tissue engineering. Here, we investigate the effects of varying concentrations of PDLLA/gelatin membranes electrospun in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP; C3H2F6O) solvent on their mechanical and physical properties as well as their biocompatibility. Regardless of the environmental conditions, increasing the gelatin content resulted in elevated stress and reduced strain at membrane failure. There was a remarkable difference in strain-to-failure between dry and wet PDLLA/gelatin membranes, with wet strains consistently higher than those of the dry membranes because of the hydrophilic nature of gelatin. A similar wet strain (εw = 2.7-3.0) was observed in PDLLA/gelatin membranes with a gelatin content between 10 and 40%. Both dry and wet stresses increased with increasing gelatin content. The dry stress on PDLLA/gelatin membranes (σd = 6.7-9.7 MPa) consistently exceeded the wet stress (σw = 4.5-8.6 MPa). The water uptake capacity (WUC) improved, increasing from 57% to 624% with the addition of 40% gelatin to PDLLA. PDLLA/gelatin hybrid membranes containing 10 to 20 wt% gelatin exhibited favorable wet mechanical properties (σw = 5.4-6.3 MPa; εw = 2.9-3.0); WUC (337-571%), degradability (11.4-20.2%), and excellent biocompatibility.

Poly(dl-lactide) Polymer Blended with Mineral Phases for Extrusion 3D Printing-Studies on Degradation and Biocompatibility

A promising therapeutic option for the treatment of critical-size mandibular defects is the implantation of biodegradable, porous structures that are produced patient-specifically by using additive manufacturing techniques. In this work, degradable poly(DL-lactide) polymer (PDLLA) was blended with different mineral phases with the aim of buffering its acidic degradation products, which can cause inflammation and stimulate bone regeneration. Microparticles of CaCO3, SrCO3, tricalcium phosphates (α-TCP, β-TCP), or strontium-modified hydroxyapatite (SrHAp) were mixed with the polymer powder following processing the blends into scaffolds with the Arburg Plastic Freeforming 3D-printing method. An in vitro degradation study over 24 weeks revealed a buffer effect for all mineral phases, with the buffering capacity of CaCO3 and SrCO3 being the highest. Analysis of conductivity, swelling, microstructure, viscosity, and glass transition temperature evidenced that the mineral phases influence the degradation behavior of the scaffolds. Cytocompatibility of all polymer blends was proven in cell experiments with SaOS-2 cells. Patient-specific implants consisting of PDLLA + CaCO3, which were tested in a pilot in vivo study in a segmental mandibular defect in minipigs, exhibited strong swelling. Based on these results, an in vitro swelling prediction model was developed that simulates the conditions of anisotropic swelling after implantation.

Resorbable bilayer membrane made of L-lactide-ε-caprolactone in guided bone regeneration: an in vivo experimental study

PURPOSE

Guided bone regeneration (GBR) is an accepted method in dental practice that can successfully increase the bone volume of the host at sites chosen for implant placement; however, existing GBR membranes exhibit rapid absorption and lack of adequate space maintenance capabilities. We aimed to compare the effectiveness of a newly developed resorbable bilayer membrane composed of poly (L-lactic acid) and poly (-caprolactone) (PLACL) with that of a collagen membrane in a rat GBR model.

METHODS

The rat calvaria was used as an experimental model, in which a plastic cylinder was placed. We operated on 40 male Fisher rats and subsequently performed micro-computed tomography and histomorphometric analyses to assess bone regeneration.

RESULTS

Significant bone regeneration was observed, which was and similar across all the experimental groups. However, after 24 weeks, the PLACL membrane demonstrated significant resilience, and sporadic partial degradation. This extended preservation of the barrier effect has great potential to facilitate optimal bone regeneration.

CONCLUSIONS

The PLACL membrane is a promising alternative to GBR. By providing a durable barrier and supporting bone regeneration over an extended period, this resorbable bilayer membrane could address the limitations of the current membranes. Nevertheless, further studies and clinical trials are warranted to validate the efficacy and safety of The PLACL membrane in humans.

Progress of biodegradable polymer application in cardiac occluders

Cardiac septal defect is the most prevalent congenital heart disease and is typically treated with open-heart surgery under cardiopulmonary bypass. Since the 1990s, with the advancement of interventional techniques and minimally invasive transthoracic closure techniques, cardiac occluder implantation represented by the Amplazter products has been the preferred treatment option. Currently, most occlusion devices used in clinical settings are primarily composed of Nitinol as the skeleton. Nevertheless, long-term follow-up studies have revealed various complications related to metal skeletons, including hemolysis, thrombus, metal allergy, cardiac erosion, and even severe atrioventricular block. Thus, occlusion devices made of biodegradable materials have become the focus of research. Over the past two decades, several bioabsorbable cardiac occluders for ventricular septal defect and atrial septal defect have been designed and trialed on animals or humans. This review summarizes the research progress of bioabsorbable cardiac occluders, the advantages and disadvantages of different biodegradable polymers used to fabricate occluders, and discusses future research directions concerning the structures and materials of bioabsorbable cardiac occluders.

Human alveolar bone-derived mesenchymal stem cell cultivation on a 3D-printed PDLLA scaffold for bone formation

This study aimed to assess effects of 3-dimensionally (3D) printed poly-d,l-lactin (PDLLA) on human alveolar bone-derived mesenchymal stem cell (h-ABMSC) osteogenic proliferation and differentiation. Human ABMSCs were cultured and identified using flow cytometry and morphological analysis. Control and PDLLA experimental groups were assessed using a Cell Counting Kit-8 (CCK-8) to detect cellular cytotoxicity and proliferative activity. Real-time quantitative polymerase chain reaction was used to determine expression levels of osteogenesis genes including alkaline phosphatase (ALP), Runt-related transcription factor 2 (Runx-2), osteopontin (OPN), and osteocalcin (OCN). The results showed that h-ABMSCs were successfully cultured and revealed by microscopic observation. Human ABMSCs were spindle-shaped, with clustered and fish-like primary cells. Cell surface markers were negative for CD34 and positive for CD44 and CD90. PDLLA had no cytotoxicity. Human ABMSCs proliferated normally, and osteogenic differentiation of the cells was observed on the surface of PDLLA. Cellular proliferative activity and expression levels of osteogenesis-related genes of PDLLA and control groups showed no significant difference, including ALP, Runx-2, OPN, and OCN. These results suggest that 3D-printed PDLLA has good cell compatibility and biological activity.

Evaluation between Biodegradable Magnesium Metal GBR Membrane and Bovine Graft with or without Hyaluronate

Bone substitutes and barrier membranes are widely used in dental regeneration procedures. New materials are constantly being developed to provide the most optimal surgical outcomes. One of these developments is the addition of hyaluronate (HA) to the bovine bone graft, which has beneficial wound healing and handling properties. However, an acidic environment that is potentially produced by the HA is known to increase the degradation of magnesium metal. The aim of this study was to evaluate the potential risk for the addition of HA to the bovine bone graft on the degradation rate and hence the efficacy of a new biodegradable magnesium metal GBR membrane. pH and conductivity measurements were made in vitro for samples placed in phosphate-buffered solutions. These in vitro tests showed that the combination of the bovine graft with HA resulted in an alkaline environment for the concentrations that were used. The combination was also tested in a clinical setting. The use of the magnesium metal membrane in combination with the tested grafting materials achieved successful treatment in these patients and no adverse effects were observed in vivo for regenerative treatments with or without HA. Magnesium based biodegradable GBR membranes can be safely used in combination with bovine graft with or without hyaluronate.

Comparison of the Fractured and Non-Fractured Orbit Before and After Surgery Using a Titanium Implant or a Resorbable Poly-d,l-lactic Acid (PDLLA) Implant: A Study from a Single Center in Niš, Serbia of 58 Patients with Unilateral Orbital Floor Fracture Using Volumetric Measurement

BACKGROUND A fracture of the orbital floor can lead to complications such as enophthalmos, impaired eye motility, or diplopia, which is why it is necessary to reconstruct the bony walls of the orbit. This study from a single center in Niš, Serbia, included 58 patients with unilateral orbital floor fracture and aimed to use volumetric measurement to compare the fractured and non-fractured orbit before and after surgery using a titanium implant or a resorbable poly-d, l-lactic acid (PDLLA) implant. MATERIAL AND METHODS From 2018 to 2022, a total of 58 patients with unilateral orbital floor fractures were treated at the Clinic of Dental Medicine, Niš. Computed tomography examination was used for volumetric measurement of the fractured and non-fractured (contralateral) orbit before and after the surgical procedure. A titanium implant was used in 31 patients, and a PDLLA implant was used in 27 patients. RESULTS Orbital volume ratio did not differ statistically significantly in relation to the type of implant (P=0.591). The postoperative volume did not differ statistically significantly from the volume of the contralateral side (titanium, P=0.212; PDLLA, P=0.232). There was a significant correlation between orbital volume and enophthalmos both before and after surgery (P=0.012, P=0.018, respectively). CONCLUSIONS Measuring the preoperative volume of the injured orbit is sufficient data for an indication because reconstruction depends primarily on the correlation between the volume and enophthalmos. The findings from this study showed that preoperative orbital volumetry using computed tomography evaluated enophthalmos and provide data to assist orbital floor reconstruction.

Additive Manufacturing of Anatomical Poly(d,l-lactide) Scaffolds

Poly(lactide) (PLA) is one of the most investigated semicrystalline polymers for material extrusion (MEX) additive manufacturing (AM) techniques based on polymer melt processing. Research on its application for the development of customized devices tailored to specific anatomical parts of the human body can provide new personalized medicine strategies. This research activity was aimed at testing a new multifunctional AM system for the design and fabrication by MEX of anatomical and dog-bone-shaped PLA samples with different infill densities and deposition angles. In particular, a commercial PLA filament was employed to validate the computer-aided design (CAD) and manufacturing (CAM) process for the development of scaffold prototypes modeled on a human bone defect. Physical-chemical characterization of the obtained samples by 1H-NMR spectroscopy, size exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) demonstrated a small reduction of polymer molecular weight (~5%) due to thermal processing, as well as that the commercial polymer employed was a semicrystalline poly(d,l-lactide). Mechanical characterization highlighted the possibility of tuning elastic modulus and strength, as well as the elongation at break up to a 60% value by varying infill parameters.

Pharmaceutical, Biomedical and Ophthalmic Applications of Biodegradable Polymers (BDPs): Literature and Patent Review

In the last few decades, the interest in biodegradable materials for biomedical applications has increased significantly. Both natural and synthetic biodegradable polymers (BDPs) have been broadly explored for various biomedical applications. These include sutures and wound dressings, screws for bone fracture, scaffolds in tissue engineering, implants, and other carriers for targeted and sustained release drug delivery. Owing to their unique characteristics, including their surface charge variable copolymer block and composition and film-forming properties, BDPs have been widely used as favourable materials for ophthalmic drug delivery. Mucoadhesive BDPs have been used in ophthalmic formulations to prolong drug retention time and improve bioavailability, allowing ophthalmic controlled release systems to design. Furthermore, BDPs-based implants, microneedles, and injectable nano- and micro-particles enabled ocular posterior segment targeting and, most importantly, circumvented the need for removing the delivery systems after application. This review outlines the major advances of BDPs and highlights the latest progress of employing natural and synthetic BDPs for various biomedical applications, emphasising the treatment and management of ophthalmic conditions.

Shape-Memory Polymers Hallmarks and Their Biomedical Applications in the Form of Nanofibers

Shape-Memory Polymers (SMPs) are considered a kind of smart material able to modify size, shape, stiffness and strain in response to different external (heat, electric and magnetic field, water or light) stimuli including the physiologic ones such as pH, body temperature and ions concentration. The ability of SMPs is to memorize their original shape before triggered exposure and after deformation, in the absence of the stimulus, and to recover their original shape without any help. SMPs nanofibers (SMPNs) have been increasingly investigated for biomedical applications due to nanofiber’s favorable properties such as high surface area per volume unit, high porosity, small diameter, low density, desirable fiber orientation and nanoarchitecture mimicking native Extra Cellular Matrix (ECM). This review focuses on the main properties of SMPs, their classification and shape-memory effects. Moreover, advantages in the use of SMPNs and different biomedical application fields are reported and discussed.

Finding the Perfect Membrane: Current Knowledge on Barrier Membranes in Regenerative Procedures: A Descriptive Review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) became common procedures in the corrective phase of periodontal treatment. In order to obtain good quality tissue neo-formation, most techniques require the use of a membrane that will act as a barrier, having as a main purpose the blocking of cell invasion from the gingival epithelium and connective tissue into the newly formed bone structure. Different techniques and materials have been developed, aiming to obtain the perfect barrier membrane. The membranes can be divided according to the biodegradability of the base material into absorbable membranes and non-absorbable membranes. The use of absorbable membranes is extremely widespread due to their advantages, but in clinical situations of significant tissue loss, the use of non-absorbable membranes is often still preferred. This descriptive review presents a synthesis of the types of barrier membranes available and their characteristics, as well as future trends in the development of barrier membranes along with some allergological aspects of membrane use.

Finding the Perfect Membrane: Current Knowledge on Barrier Membranes in Regenerative Procedures: A Descriptive Review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) became common procedures in the corrective phase of periodontal treatment. In order to obtain good quality tissue neo-formation, most techniques require the use of a membrane that will act as a barrier, having as a main purpose the blocking of cell invasion from the gingival epithelium and connective tissue into the newly formed bone structure. Different techniques and materials have been developed, aiming to obtain the perfect barrier membrane. The membranes can be divided according to the biodegradability of the base material into absorbable membranes and non-absorbable membranes. The use of absorbable membranes is extremely widespread due to their advantages, but in clinical situations of significant tissue loss, the use of non-absorbable membranes is often still preferred. This descriptive review presents a synthesis of the types of barrier membranes available and their characteristics, as well as future trends in the development of barrier membranes along with some allergological aspects of membrane use.

Enhanced cellular engraftment of adipose-derived mesenchymal stem cell spheroids by using nanosheets as scaffolds

The short survival time of transplanted adipose-derived mesenchymal stem cells (ASCs) is a problem for skin wound healing. Transplantation after the formation of cellular spheroids has been investigated as a promising method for prolonging cellular survival. However, there have been technical restrictions for transplantation of spheroids in clinical practice. Here, we show an effective method for transplantation of ASC spheroids onto skin wounds in order to efficiently cure refractory ulcers. To assist anchoring of spheroids onto skin wounds, we used a 120-nm-thick free-standing film (nanosheet) that has a highly adhesive property. Bioluminescence imaging showed that ASC spheroids carried by the nanosheet survived for 14 days, which is about two-times longer than that previously reported. Wounds treated with a nanosheet carrying ASC spheroids were 4-times smaller than untreated wounds on day 14. This method for transplantation of spheroids could be applied to cell therapy for various refractory skin wounds.

Bioabsorbable System-Related Subcutaneous Swelling After Craniofacial Surgery

BACKGROUND

Bioabsorbable systems have been commonly used in pediatric patients for primary cranioplasty and other related surgeries. However, subcutaneous swelling, a unique complication related to bioabsorbable osteosynthesis, is a concern. Differences in the incidence of subcutaneous swelling, depending on the bioabsorbable material used to construct the plate, are still unknown.

METHODS

The authors retrospectively reviewed all incidences of subcutaneous swelling related to resorbable systems used during primary cranioplasty for patients with craniosynostosis at their hospital between 2014 and 2018 during a 12-month follow-up period. Furthermore, the authors reviewed all published English-language articles (since 1995) on subcutaneous swelling in bioabsorbable systems used for craniosynostosis.

RESULTS

The most common resorbable systems used in the literature were divided into 2 groups: mixtures of poly D-lactic acid and polyglycolic acid, and mixtures of poly D- and L-lactic acid. In patients for whom poly D-lactic acid and polyglycolic acid were used, the incidence of subcutaneous swelling during resorption was 0% to 4.2% between 3 and 9 months of follow-up. In patients for whom poly D- and L-lactic acid was used, subcutaneous swelling during resorption occurred in 5% to 16.7% of these patients between 6 and 12 months of follow-up. All cases resolved spontaneously after complete absorption of the plate.

CONCLUSIONS

It was difficult to determine which system had the lowest incidence of subcutaneous swelling. The thickness of each resorbable system and the thickness of the infants' scalps were different in each study. However, subcutaneous swelling occurred in every resorbable system. Therefore, preoperative counseling and careful follow-up are necessary.

Barrier membranes for tissue regeneration in dentistry

Background: In dentistry, barrier membranes are used for guided tissue regeneration (GTR) and guided bone regeneration (GBR). Various membranes are commercially available and extensive research and development of novel membranes have been conducted. In general, membranes are required to provide barrier function, biosafety, biocompatibility and appropriate mechanical properties. In addition, membranes are expected to be bioactive to promote tissue regeneration.

Objectives: This review aims to organize the fundamental characteristics of the barrier membranes that are available and studied for dentistry, based on their components.

Results: The principal components of barrier membranes are divided into nonbiodegradable and biodegradable materials.

Nonbiodegradable membranes are manufactured from synthetic polymers, metals or composites of these materials. The first reported barrier membrane was made from expanded polytetrafluoroethylene (e-PTFE). Titanium has also been applied for dental regenerative therapy and shows favorable barrier function. Biodegradable membranes are mainly made from natural and synthetic polymers. Collagens are popular materials that are processed for clinical use by cross-linking. Aliphatic polyesters and their copolymers have been relatively recently introduced into GTR and GBR treatments. In addition, to improve the tissue regenerative function and mechanical strength of biodegradable membranes, inorganic materials such as calcium phosphate and bioactive glass have been incorporated at the research stage.

Conclusions: Currently, there are still insufficient guidelines for barrier membrane choice in GTR and GBR, therefore dentists are required to understand the characteristics of barrier membranes.

Foreign Body Reaction to Poly-D-L-Lactic Acid Resorbable Plates Used in Craniofacial Surgery

Resorbable surgical materials are often used in the pediatric population to provide fixation in the growing skeleton. Although foreign body reactions to poly-D-L-lactic acid (PDLLA) plates and screws have been previously reported in other fields, to date PDLLA polymers have been well-tolerated in the setting of craniofacial surgery. The authors report a case of a previously healthy 4-month-old patient with Crouzon syndrome who underwent a frontal-orbital advancement with resorbable PDLLA plates and screws and subsequently experienced extensive foreign body reactions and wound healing complications.

Ultrasound-Activated Bioresorbable Osteosynthesis in the Treatment of Craniosynostosis

ABSTRACT

The purpose of this study is to estimate the incidence of fixation-related complications following ultrasound-activated biodegradable osteosynthesis (UBO) in the treatment of craniosynostosis. The authors searched MEDLINE, PubMed, Embase, Google Scholar, and Cochrane Library from January 2005 to January 2020 for clinical studies reporting the use of UBO for fixation in the treatment of craniosynostosis. The primary outcome was the incidence of fixation-related complications, including unstable fixation; swelling, plate visibility, or palpability; infection; inflammation, sinus formation, and discharge; implant exposure; reoperation or implant removal. The pooled incidence rates were estimated using random-effects models. Of 155 studies identified, 10 were included, representing 371 patients. Forty-six (12.4%) patients presented fixation-related complications. The incidence rates of swelling/visibility/palpability, infection, and reoperation/implant removal were pooled based on the available data. The pooled incidence rate of chronic swelling/visibility/palpability was 0.21 (95% confidence interval [CI], 0.05-0.43). Sensitivity analysis by omitting the outlier study demonstrates that the incidence of swelling/visibility/palpability was 0.07 (95% CI, 0.04-0.11). The pooled incidence rate of infection and reoperation/implant removal was 0.07 (95% CI, 0.01-0.16) and 0.04 (95% CI, 0.01-0.09), respectively. Results show that although UBO can provide stable fixation, chronic swelling/visibility/palpability, infection, and reoperation for removal are not uncommon. Based on the literature, the authors recommend judicious use of UBO in patients with large frontorbital advancement and in the area of the coronal suture or other sites with thin overlying skin/subcutaneous tissue. The high possibility of chronic swelling/palpability/visibility during degradation, needs to be discussed preoperatively.

Efficient differentiation and polarization of primary cultured neurons on poly(lactic acid) scaffolds with microgrooved structures

Synthetic biodegradable polymers including poly(lactic acid) (PLA) are attractive cell culture substrates because their surfaces can be micropatterned to support cell adhesion. The cell adhesion properties of a scaffold mainly depend on its surface chemical and structural features; however, it remains unclear how these characteristics affect the growth and differentiation of cultured cells or their gene expression. In this study, we fabricated two differently structured PLA nanosheets: flat and microgrooved. We assessed the growth and differentiation of mouse primary cultured cortical neurons on these two types of nanosheets after pre-coating with poly-D-lysine and vitronectin. Interestingly, prominent neurite bundles were formed along the grooves on the microgrooved nanosheets, whereas thin and randomly extended neurites were only observed on the flat nanosheets. Comparative RNA sequencing analyses revealed that the expression of genes related to postsynaptic density, dendritic shafts, and asymmetric synapses was significantly and consistently up-regulated in cells cultured on the microgrooved nanosheets when compared with those cultured on the flat nanosheets. These results indicate that microgrooved PLA nanosheets can provide a powerful means of establishing a culture system for the efficient and reproducible differentiation of neurons, which will facilitate future investigations of the molecular mechanisms underlying the pathogenesis of neurological disorders.