Therapeutic doses of radiation alter proliferation and attachment of osteoblasts to implant surfaces.

Osseointegration of implants in irradiated bone is inadequate. The effect of radiation on cell-implant material interaction has not been adequately studied. The goal of this study was to investigate the effects of ionizing radiationon the proliferation, differentiation, and attachment of osteoblasts to commercially pure titanium (cpTi). Human fetal osteoblasts (hFOB) were irradiated either before or after plating in tissue culture (TC) dishes with or without cpTi disks. Radiation was single dose of 10 cGy, 25 cGy, 50 cGy, 1 Gy, 2 Gy, 4 Gy or 8 Gy. Cell proliferation was determined by counting trypsinized cells on 7 days after irradiation. Attachment of irradiated hFOB was measured indirectly by counting cells 2 and 6 h after plating. Differentiation was evaluated by alkaline phosphatase activity. Compared with nonirradiated sham controls, higher doses of radiation significantly reduced cell attachment and proliferation. Both proliferation and attachment were significantly lower on cpTi compared with TC. Attachment decreased based on the length of postirradiation period. Although differentiation was significantly enhanced by a dose of 8 Gy, proliferation was lowest. These initial studies show that effects of therapeutic doses of radiation on osteoblasts varied depending on the surface, time-elapsed, and amount of radiation.

Osteoblastic phenotype expression of MC3T3-E1 cultured on electrospun polycaprolactone fiber mats filled with hydroxyapatite nanoparticles.

Electrospun (e-spun) fiber mats of polycaprolactone (PCL; Mn = 80 000 g mol-1) with or without the presence of hydroxyapatite (HAp) nanoparticles (at 1% w/v based on the volume of the PCL solution) were successfully fabricated. The potential for use of these e-spun fiber mats as bone scaffolds was assessed by mouse calvaria-derived pre-osteoblastic cells, MC3T3-E1, in terms of attachment, proliferation, differentiation, and mineralization. Despite the lower number of cells attached at early time points, both the fibrous scaffolds supported the proliferation of MC3T3-E1 at similar levels to tissue-culture polystyrene plate (TCPS), with the cells growing on the PCL/HAp fiber mat (i.e., PCL/HAp-FS) showing the greatest proliferation rate on day 3 after the initial attachment period of 16 h. Alkaline phosphatase (ALP) activity of the cells grown on TCPS was the greatest on day 3 after cell culturing, while that of the cells grown on PCL/HAp-FS reached a maximum on day 5. On the other hand, the ALP activity of the cells grown on the neat PCL fiber mat (i.e., PCL-FS) was the lowest at any given time point. MC3T3-E1 cultured on the surface of PCL/HAp-FS expressed the greatest amount of osteocalcin (OC) gene on day 14 after cell culturing and OC protein on day 21 after cell culturing, respectively, when compared with those cultured on the surfaces of PCL-FS and TCPS. This corresponded to the greatest extent of mineralization for the cells grown on the surface of PCL/HAp-FS on day 21, followed by that for the cells grown on PCL-FS and TCPS, respectively.

In vitro biocompatibility of schwann cells on surfaces of biocompatible polymeric electrospun fibrous and solution-cast film scaffolds.

The in vitro responses of Schwann cells (RT4-D6P2T, a schwannoma cell line derived from a chemically induced rat peripheral neurotumor) on various types of electrospun fibrous scaffolds of some commercially available biocompatible and biodegradable polymers, i.e., poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polycaprolactone (PCL), poly(l-lactic acid) (PLLA), and chitosan (CS), were reported in comparison with those of the cells on corresponding solution-cast film scaffolds as well as on a tissue-culture polystyrene plate (TCPS), used as the positive control. At 24 h after cell seeding, the viability of the attached cells on the various substrates could be ranked as follows: PCL film > TCPS > PCL fibrous > PLLA fibrous > PHBV film > CS fibrous approximately CS film approximately PLLA film > PHB film > PHBV fibrous > PHB fibrous. At day 3 of cell culture, the viability of the proliferated cells on the various substrates could be ranked as follows: TCPS > PHBV film > PLLA film > PCL film > PLLA fibrous > PHB film approximately PCL fibrous > CS fibrous > CS film > PHB fibrous > PHBV fibrous. At approximately 8 h after cell seeding, the cells on the flat surfaces of all of the film scaffolds and that of the PCL nanofibrous scaffold appeared in their characteristic spindle shape, while those on the surfaces of the PHB, PHBV, and PLLA macrofibrous scaffolds also appeared in their characteristic spindle shape, but with the cells being able to penetrate to the inner side of the scaffolds.

Preparation of electrospun silk fibroin fiber mats as bone scaffolds: a preliminary study.

In the present contribution, electrospinning (e-spinning) was used to fabricate ultra-fine fibers of silk fibroin (SF) from cocoons of indigenous Thai silkworms (Nang-Lai) and Chinese/Japanese hybrid silkworms (DOAE-7). The effects of solution concentration (i.e., 10-40% (w/v) in 85% (v/v) formic acid) and applied electrostatic field strength (EFS; 10, 15 and 20 kV/10 cm) on morphology and size of the electrospun (e-spun) SF products were investigated by scanning electron microscopy. The average diameter of the resulting e-spun SF fibers was found to increase with an increase in both the solution concentration and the EFS value. Specifically, the average diameter of the e-spun SF fibers from Nang-Lai SF solutions ranged between 217 and 610 nm, while that of the fibers from DOAE-7 SF solutions ranged between 183 and 810 nm. The potential for use of the e-spun SF fiber mats as bone scaffolds was assessed with mouse osteoblast-like cells (MC3T3-E1) in which the cells appeared to adhere and proliferate well on their surface.

Novel bone scaffolds of electrospun polycaprolactone fibers filled with nanoparticles.

Novel bone scaffolding materials were successfully fabricated by electrospinning from polycaprolactone (PCL) solutions containing nanoparticles of calcium carbonate (CaCO3) or hydroxyapatite (HA). The potential use of the electrospun fibrous scaffolds for bone regeneration was evaluated in vitro with human osteoblasts (SaOS2) in terms of attachment, proliferation, and alkaline phosphatase (ALP) activity of the cells that were cultured directly on the scaffolds. The results were compared with those on corresponding solution-cast film scaffolds and tissue-culture polystyrene plate (TCPS). It was found that all of the fibrous scaffolds promoted much better adhesion and proliferation of cells than the corresponding film scaffolds and TCPS. Interestingly, the cells that were seeded on all of the fibrous scaffolds appeared to be well-expanded and attach on the fiber surface very well even only about 1 hr in culture, while those seeded on all of the film scaffolds and the glass substrate were still in round shape. Among the various fibrous scaffolds investigated, the one that was filled with 1.0% HA showed the highest ALP activity. Finally, all of the fibrous scaffolds exhibited much greater tensile strength at yield than all of the corresponding film scaffolds.

Preparation and characterization of novel bone scaffolds based on electrospun polycaprolactone fibers filled with nanoparticles.

Novel bone-scaffolding materials were successfully fabricated by electrospinning from polycaprolactone (PCL) solutions containing nanoparticles of calcium carbonate (CaCO(3)) or hydroxyapatite (HA). The diameters of the as-spun fibers were found to increase with the addition and increasing amounts of the nanoparticles. The observed increase in the diameters of the as-spun fibers with the addition and increasing amounts of the nanoparticulate fillers was responsible for the observed increase in the tensile strength of the obtained fiber mats. An increase in the concentration of the base PCL solution caused the average diameter of the as-spun PCL/HA composite fibers to increase. Increasing applied electrical potential also resulted in an increase in the diameters of the obtained PCL/HA composite fibers. Lastly, indirect cytotoxicity evaluation of the electrospun mats of PCL, PCL/CaCO(3), and PCL/HA fibers based on human osteoblasts (SaOS2) and mouse fibroblasts (L929) revealed that these as-spun mats posed no threat to the cells, a result that implied their potential for utilization as bone-scaffolding materials.