How do we control the size and shape of pores in 3D scaffolds?

This article was directed and written by Dr. Lucía Pérez Sánchez, Ldi. Misael A. Ortiz de la O, Dr. Marco Antonio Álvarez Pérez and Dr. Janeth Serrano Bello (Laboratorio de Bioingeniería de Tejidos, División de Estudios de Posgrado e Investigación, Facultad de Odontología, UNAM) Dra. Monserrat Llaguno Munive (Laboratorio de Física Médica, Subdirección de Investigación Básica, Instituto Nacional de Cancerología) and Dr. Osmar A. Chanes Cuevas (Laboratorio de Investigación de Materiales Dentales y Biomateriales, División de Estudios de Posgrado e Investigación, Facultad de Odontología, UNAM). One of the significant challenges in tissue engineering is to fabricate customized scaffolds, control the microarchitecture's precision, the pores' size and shape, and regenerate defects of critical size in bone tissue. For this reason, the authors of this project decided to design a scaffold that had an exact size to the bone defect, using microtomographic images of a critical size bone defect in Wistar rat calvaria, with the scaffold-specific features such as different pore sizes (graded porosity) and three different types of pores (closed, blind and open), with the scaffold having different pore sizes (graded porosity) and three different types of pores (closed, blind and open), with the scaffold specific features such as The main objective, is to generate topological signals for the cells that favour bone regeneration, justifying this design in reported studies where they indicate that the size and shape of the pores cause a change in the cellular response and also favour vascularization in the defect area. To fabricate the scaffold, the authors decided to use the Fused Deposition Modeling (FDM) printing technique with the polymer filament of Poly Lactic Acid (PLA); this technique allows control of the pores' size and shape. However, it is necessary to standardize the printing parameters to achieve the desired shape and pore sizes; therefore, In this project, more than 50 printing parameters were standardized using Ultimaker Cura software; once this action was performed, the exact scaffold was printed to the bone defect with different pore sizes (200 microns - 700 microns), where the smallest pores were concentrated at the edge of the scaffold. The most prominent pores in the centre of the scaffold and the three types of pores were included. Once the scaffolds were printed, their surface characteristics were evaluated by scanning electron microscopy (SEM) images, their mechanical properties (Young's modulus and maximum stress), and their cellular response with the cell viability assay using dental pulp-derived mesenchymal stem cells (DPSC). It is essential to highlight that the results showed that the size and shape of the scaffold pores could be controlled by standardizing the printing parameters since the authors compared the diameter of the printed versus designed pores using a U-Mann Whitney statistical analysis; on the other hand, concerning the cell viability results, the DPSC cells remained viable on days 3 and 7, showing a favourable cellular response, which could be verified in the SEM images where the cells were observed adhering to the scaffold and forming cellular conglomerates. Therefore, the use of this type of scaffold is promising for the field of tissue engineering and regeneration of bone defects of critical size.

See the article:

Standardization of 3D printing parameters to control the size and shape of pores in Polylactic acid scaffolds

https://doi.org/10.1002/mba2.74