Improved Mesenchymal Stem Cell Seeding on RGD‐Modified Poly(L‐lactic acid) Scaffolds using Flow Perfusion

Abstract

Arg-Gly-Asp (RGD) has been widely utilized to increase cell adhesion to three-dimensional scaffolds for tissue engineering. However, cell seeding on these scaffolds has only been carried out statically, which yields low cell seeding efficiencies. We have characterized, for the first time, the seeding of rat mesenchymal stem cells on RGD-modified poly(L-lactic acid) (PLLA) foams using oscillatory flow perfusion. The incorporation of RGD on the PLLA foams improves scaffold cellularity in a dose-dependent manner under oscillatory flow perfusion seeding. When compared to static seeding, oscillatory flow perfusion is the most efficient seeding technique. Cell detachment studies show that cell adhesion is dependent on the applied flow rate, and that cell attachment is strengthened at higher levels of RGD modification.

Effect of surface acoustic waves on the viability, proliferation and differentiation of primary osteoblast-like cells

“…As compared to the methods described in the literature, 4,[6][7][8][9][10][11][12] where the seeding process usually takes hours to days, the present SAW method significantly accelerates the cell seeding process. The fast seeding time also means that multiple drops containing the cells can be successively driven into the scaffold to achieve greater cell loading.…”

“…As we mentioned before, there are various cell seeding methods being developed and most of these studies investigate the cell viability and functionality. 4,[6][7][8][9][10][11][12] Undoubtedly, cell viability and functionality are critical to the usefulness of any new technique for tissue engineering. 5 Therefore, in addition to high cell viability, the proliferation and differentiation ability of the treated cells showed no difference from those of the untreated cells, indicating that the SAW has no deleterious effects on the cells' functionality.…”

“…However, low seeding efficiencies and nonuniform cell distributions have been reported with these methods as well. [3][4][5][6][7][8][9][10][11][12] Alvarez-Barreto and co-workers 10,11 developed a more refined approach from these ideas using flow perfusion; a cell suspension is first poured on top of the prewetted scaffold and then the flow is drawn into the scaffold by oscillatory pumping across it, driving the fluid with the suspended cells into the scaffold matrix. Compared to past methods, this technique has been reported to deliver superior cell adhesion and seeding efficiency.…”

“…However, even this perfusion method is slow, requiring 1-2 h. Moreover, large fluid pumps are required to compensate for the large pressure drops associated with the high capillary stresses resisting the flow of the fluid through the scaffold, a notable limitation in miniaturizing the technology to dimensions appropriate for point-of-care use. 10,11 We reported in a previous work another method 13 using surface acoustic wave ͑SAW͒ radiation 14 to provide the perfusion force. In that work, we demonstrated that small ͑10 ᐉ͒ suspensions of microparticles may be rapidly driven into a porous polycaprolactone ͑PCL͒ scaffold in 10 s, some three to four orders of magnitude faster than the hour-long process required using the static and perfusion methods described above.…”

Influence of Shear Stress in Perfusion Bioreactor Cultures for the Development of Three-Dimensional Bone Tissue Constructs: A Review

“…In the majority of the literature surveyed, an attachment time of 24-72 h was allowed before the application of shear stress. In some instances, dynamic seeding 88,89 of cells was conducted in an effort to improve cell distribution within the scaffold, followed by either a static period or low flow period to enhance cell attachment strength or increase proliferation (cells may have been cultured in normal or differentiation medium for up to 14 days…”