Influence of Molecular Weight and Crystallinity of Poly(L-Lactic Acid) on the Adhesion and Proliferation of Human Osteoblast Like Cells

Abstract

The molecular weight and crystallinity of systems based on poly(L-lactic acid) PLLA is an important issue as it can influence, besides the general physical properties of the polymer, the patterns of cell adhesion, proliferation and cell morphology. The objective of the present study was to evaluate how crystallinity and molecular weight of PLLA influence the referred parameters. Four conditions were tested: low molecular weight amorphous and semi-crystalline PLLA disks, and high molecular weight amorphous and semi-crystalline PLLA disks, obtained from hot press. The thermal properties of the studied materials were accessed by differential scanning calorimetry. For the cell culture studies a human osteosarcoma cell line (SaOS-2) was chosen. Disks were immersed in a cell suspension containing 5x104 cells/ml and kept in culture for periods up to two weeks. Cell viability and proliferation of SaOS-2 cells was assessed by MTS test and a total protein assay, respectively. The adhesion and morphology of SaOS-2 cells on PLLA disks was assessed by scanning electronic microscopy. Results showed that cell viability was not affected by the different tested conditions. However, cell proliferation was increased in the high molecular weight amorphous samples and cells seemed to have higher adhesion patterns on semi-crystalline samples. This is probably happening due to different rates of integrin interaction with the substrate leading to different patterns of focal adhesion points formation.

Influence of crystallinity and fiber orientation on hydrophobicity and biological response of poly(l-lactide) electrospun mats

“…It is interesting to notice at this point that the variations in the degree of crystallinity in PLLA films does not imply significant variations either in the contact angle (74º +/-3 for 10% and 67% crystalline samples) [41] nor in the stiffness (Young Modulus of 3.4+/-0.3 and 3.5+/-0.2 GPa for 7% and 40-50% crystalline samples) [42]. When the amorphous electrospun fibrils crystallize their stiffness and surface energy increase [22,43], and at the same time surface nano-roughness is expected to be developed.…”

Thermomechanical Properties of Polylactic Acid-Graphene Composites: A State-of-the-Art Review for Biomedical Applications

“…Sladago et al [ 59 ] reported a study to evaluate how crystallinity and molecular weight of PLLA influenced the patterns of cell adhesion, proliferation, and cell morphology parameters. Four conditions were tested: low molecular weight amorphous and semi-crystalline hot-pressed PLLA disks (PLLA1-A and PLLA1-SC), and high molecular weight amorphous and semi-crystalline hot-pressed PLLA disks (PLLA2-A and PLLA2-SC).…”

“… SEM micrographs of human osteoblasts like cells after two weeks in culture ( a ) amorphous PLLA1; ( b ) semi-crystalline PLLA1; ( c ) Cell viability measured from the optical density (O.D.) at 490 nm; and ( d ) Cell proliferation assays on SaOS-2 cells grown on PLLA disks, (PLLA1—low molecular weight; PLLA2—high molecular weight; A—amorphous; SC—Semi-crystalline) [ 59 ]. …”

Structural evolution of the amorphous phase during crystallization of poly(l-lactic acid): A synchrotron wide-angle X-ray scattering study

“…This polymer is also an environmentally compostable material and, hence, it has been proposed for eco-friendly applications [3,4]. PLLA may crystallize slowly [7][8][9], and it is well-known that the presence of crystallinity has a profound impact on its physical properties, degradation profile and cell behavior [10][11][12][13][14][15]. Different techniques may be used to screen the evolution of the crystalline fraction during crystallization.…”