Concave pit-containing scaffold surfaces improve stem cell-derived osteoblast performance and lead to significant bone tissue formation.
BACKGROUND
Scaffold surface features are thought to be important regulators of stem cell performance and endurance in tissue engineering applications, but details about these fundamental aspects of stem cell biology remain largely unclear.


RESULTS
In the present study, smooth clinical-grade lactide-coglyolic acid 85:15 (PLGA) scaffolds were carved as membranes and treated with NMP (N-metil-pyrrolidone) to create controlled subtractive pits or microcavities. Scanning electron and confocal microscopy revealed that the NMP-treated membranes contained: (i) large microcavities of 80-120 microm in diameter and 40-100 microm in depth, which we termed primary; and (ii) smaller microcavities of 10-20 microm in diameter and 3-10 microm in depth located within the primary cavities, which we termed secondary. We asked whether a microcavity-rich scaffold had distinct bone-forming capabilities compared to a smooth one. To do so, mesenchymal stem cells derived from human dental pulp were seeded onto the two types of scaffold and monitored over time for cytoarchitectural characteristics, differentiation status and production of important factors, including bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF). We found that the microcavity-rich scaffold enhanced cell adhesion: the cells created intimate contact with secondary microcavities and were polarized. These cytological responses were not seen with the smooth-surface scaffold. Moreover, cells on the microcavity-rich scaffold released larger amounts of BMP-2 and VEGF into the culture medium and expressed higher alkaline phosphatase activity. When this type of scaffold was transplanted into rats, superior bone formation was elicited compared to cells seeded on the smooth scaffold.


CONCLUSIONS
In conclusion, surface microcavities appear to support a more vigorous osteogenic response of stem cells and should be used in the design of therapeutic substrates to improve bone repair and bioengineering applications in the future.
Graziano
Antonio
A
Dipartimento di Medicina Sperimentale, Sezione di Istologia ed Embriologia, Secondo Ateneo di Napoli, Naples, Italy.
d'Aquino
Riccardo
R
Cusella-De Angelis
Maria Gabriella
MG
Laino
Gregorio
G
Piattelli
Adriano
A
Pacifici
Maurizio
M
De Rosa
Alfredo
A
Papaccio
Gianpaolo
G
D000328:Adult; D000818:Animals; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D016867:Immunocompromised Host; D007124:Immunoenzyme Techniques; D019344:Lactic Acid / Q000378:metabolism; D008875:Middle Aged; D010006:Osteoblasts / Q000502:physiology* / Q000648:ultrastructure; D010012:Osteogenesis / Q000502:physiology*; D011100:Polyglycolic Acid / Q000378:metabolism; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011760:Pyrrolidinones / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013234:Stem Cells / Q000502:physiology* / Q000648:ultrastructure; D017154:Stromal Cells / Q000502:physiology / Q000648:ultrastructure; D023822:Tissue Engineering; D054457:Tissue Scaffolds; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D055815:Young Adult
D011760:Pyrrolidinones; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C038678:N-methylpyrrolidone