Fetal Cartilage-Derived Cells Have Stem Cell Properties and Are a Highly Potent Cell Source for Cartilage Regeneration

Current strategies for cartilage cell therapy are mostly based on the use of autologous chondrocytes or mesenchymal stem cells (MSCs). However, these cells have limitations of a small number of cells available and of low chondrogenic ability, respectively. Many studies now suggest that fetal stem cells are more plastic than adult stem cells and can therefore more efficiently differentiate into target tissues. However, the characteristics and the potential of progenitor cells from fetal tissue remain poorly defined. In this study, we examined cells from human fetal cartilage at 12 weeks after gestation in comparison with bone marrow-derived MSCs or cartilage chondrocytes from young donors (8-25 years old). The fetal cartilage-derived progenitor cells (FCPCs) showed higher yields by approximately 24 times than that of chondrocytes from young cartilage. The morphology of the FCPCs was polygonal at passage 0, being similar to that of the young chondrocytes, but it changed later at passage 5, assuming a fibroblastic shape more akin to that of MSCs. As the passages advanced, the FCPCs showed a much greater proliferation ability than the young chondrocytes and MSCs, with the doubling times ranging from 2∼4 days until passage 15. The surface marker profile of the FCPCs at passage 2 was quite similar to that of the MSCs, showing high expressions of CD29, CD90, CD105, and Stro-1. When compared to the young chondrocytes, the FCPCs showed much less staining of SA-β-gal, a senescence indicator, at passage 10 and no decrease in SOX9 expression until passage 5. They also showed a much greater chondrogenic potential than the young chondrocytes and the MSCs in a three-dimensional pellet culture in vitro and in polyglycolic acid (PGA) scaffolds in vivo. In addition, they could differentiate into adipogenic and osteogenic lineages as efficiently as MSCs in vitro. These results suggest that FCPCs have stem cell properties to some extent and that they are more active in terms of proliferation and chondrogenic differentiation than young chondrocytes or MSCs.

Bilateral occurrence and morphologic analysis of complete discoid lateral meniscus

PURPOSE

The aim of the study was to investigate and analyze bilateral incidence and morphology of complete discoid lateral meniscus (DLM) with possible relation to tears and symptoms in knee joints.

MATERIALS AND METHODS

Thirty-eight consecutive patients with symptomatic or already-torn complete DLM on magnetic resonance imaging in a unilateral knee underwent diagnostic arthroscopy on both knee joints upon agreement. The presence and shape of complete DLM as well as presence and pattern of tear were recorded accordingly.

RESULTS

In total, 89.5% (34 of 38 patients) showed bilateral complete DLM, and 84.2% yielded bilateralism with identical shape. Cape-slab was the most frequent shape, comprising 68.8% of patients with identically-shaped bilateral DLM overall. Tear patterns were more frequent, in the order of longitudinal, simple horizontal, radial, and degenerative; however, the morphological shape of complete DLM was not significantly related to tear incidence or pattern. Meniscus tears and knee symptoms occurred in the contralateral knee with incidences of 32.4% and 26.5% in patients with bilateral complete DLM, respectively.

CONCLUSION

Based on these findings, more aggressive warning on the presence of discoid pathology and the need for evaluation on the contralateral knee should be considered during consultation with patients with symptomatic complete DLM in a unilateral knee in the outpatient clinic.

Electron-boson spectral density of LiFeAs obtained from optical data

We analyze existing optical data in the superconducting state of LiFeAs at T = 4 K, to recover its electron-boson spectral density. A maximum entropy technique is employed to extract the spectral density I(2)χ(ω) from the optical scattering rate. Care is taken to properly account for elastic impurity scattering which can importantly affect the optics in an s-wave superconductor, but does not eliminate the boson structure. We find a robust peak in I(2)χ(ω) centered about Ω(R) ≅ 8.0 meV or 5.3 k(B)Tc (with Tc = 17.6 K). Its position in energy agrees well with a similar structure seen in scanning tunneling spectroscopy (STS). There is also a peak in the inelastic neutron scattering (INS) data at this same energy. This peak is found to persist in the normal state at T = 23 K. There is evidence that the superconducting gap is anisotropic as was also found in low temperature angular resolved photoemission (ARPES) data.

A superficial hyperechoic band in human articular cartilage on ultrasonography with histological correlation: preliminary observations

Purpose:

To demonstrate the superficial hyperechoic band (SHEB) in articular cartilage by using ultrasonography (US) and to assess its correlation with histological images.

Methods:

In total, 47 regions of interest (ROIs) were analyzed from six tibial osteochondral specimens (OCSs) that were obtained after total knee arthroplasty. Ultrasonograms were obtained for each OCS. Then, matching histological sections from all specimens were obtained for comparison with the ultrasonograms. Two types of histological staining were used: Safranin-O stain (SO) to identify glycosaminoglycans (GAG) and Masson’s trichrome stain (MT) to identify collagen. In step 1, two observers evaluated whether there was an SHEB in each ROI. In step 2, the two observers evaluated which histological staining method correlated better with the SHEB by using the ImageJ software.

Results:

In step 1 of the analysis, 20 out of 47 ROIs showed an SHEB (42.6%, kappa=0.579). Step 2 showed that the SHEB correlated significantly better with the topographical variation in stainability in SO staining, indicating the GAG distribution, than with MT staining, indicating the collagen distribution (P<0.05, kappa=0.722).

Conclusion:

The SHEB that is frequently seen in human articular cartilage on high-resolution US correlated better with variations in SO staining than with variations in MT staining. Thus, we suggest that a SHEB is predominantly related to changes in GAG. Identifying an SHEB by US is a promising method for assessing the thickness of articular cartilage or for monitoring early osteoarthritis.

Detection of CTX-II in serum and urine to diagnose osteoarthritis by using a fluoro-microbeads guiding chip

This study reports a new strategy for simultaneous detection of the C-telopeptide fragments of type II collagen (CTX-II) as a biomarker of osteoarthritis (OA) using a fluoro-microbeads guiding chip. As osteoarthritis progresses, the joint components including matrix and cartilage are degraded by proteases. The degraded products such as CTX-II are released into the serum and urine, and the CTX-II concentration in body fluids reflects OA progression. Because the CTX-II has heterogeneous epitope structure in serum (sCTX-II; homodimers) and urine (uCTX-II; monomers or variant monomers), a multiple-sensing device enabling both sandwich and competitive-type immunoassays is required. For multiple assessments of serum and urinary CTX-II, we designed a fluoro-microbeads guiding chip (FMGC) containing multiple sensing areas and connecting channels. Using the approach, the sandwich (sCTX-II) and competition (uCTX-II) assays could be simultaneously performed on a single chip. We designed a fluidic control device enabling selective control of the open-close function of FMGC channels. The immune-specific signal was quantitatively analyzed by counting the number of fluorescent microbeads from the registered images. The results from the developed FMGC assay showed high correlation with those obtained in ELISA. The completion time of the FMGC assay was 24-fold and 3.5-fold shorter than the ELISA for urinary and serum CTX-II. Taken together, it enabled the simultaneous detection of both sCTX-II and uCTX-II. This FMGC-based assay would be a promising tool for monitoring of osteoarthritis.

Geometrical spin frustration in Pr5Ni2Si3 composed of triangular crystal lattices

We have studied the transport, magnetic and thermal properties of Pr5Ni2Si3 with complex triangular lattices under various magnetic fields. The ferromagnetic transitions in the basal plane were observed at T(C1) = 52 K and T(C2) = 65 K. A decrease in magnetization below 30 K and the reduced paramagnetic Curie temperature θP are indicative of the development of antiferromagnetic correlation. These features are well understood by the frustration effect of the magnetic moments of Pr ions which constitute the triangular structural unit. The frustration caused the rapid rise of electrical resistivity below 30 K and an enormous entropy in low-temperature regions. The antiferromagnetic correlation acting between the frustrated Pr ions never causes any long-range order down to 0.6 K.

Difference in knee rotation between total and unicompartmental knee arthroplasties during stair climbing

PURPOSE

The purpose of this study was to compare knee kinematics during stair walking in patients with simultaneous total knee arthroplasty (TKA) and unicompartmental knee arthroplasties (UKA). It was hypothesized that UKA would reproduce more normalized knee kinematics than TKA during stair ascent and descent.

METHODS

Six patients who received UKA in one knee and TKA in the other knee were included in the study. For this study, a four-step staircase was assembled with two force platforms being positioned at the centre of the second and third steps. Each patient was attached with 16 reflective markers at both lower extremities and was asked to perform five roundtrip trials of stair climbing. Kinematic parameters including stance duration, knee angle, vertical ground reaction force (GRF), joint reaction force, and moments were obtained and analysed using a10-camera motion system (VICON, Oxford, UK). Nonparametric Friedman test was used to compare the results between two arthroplasty methods and between stair ascent and descent.

RESULTS

Compared to TKA, UKA knees exhibited significantly greater degree of rotation in transverse planes (5.0 degrees during ascent and 6.0 degrees during descent on average), but showed no difference in terms of the other parameters. When comparing the results during stair ascent with descent, overall greater knee angle, vertical GRF, joint reaction force, and moment were observed during stair descent.

CONCLUSIONS

Both UKA and TKA knees have shown overall similar knee kinematics, though UKA knee may allow greater degree of rotation freedom, which resembles normal knee kinematics during stair walking.

An autologous bone marrow mesenchymal stem cell-derived extracellular matrix scaffold applied with bone marrow stimulation for cartilage repair

PURPOSE

It is well known that implanting a bioactive scaffold into a cartilage defect site can enhance cartilage repair after bone marrow stimulation (BMS). However, most of the current scaffolds are derived from xenogenous tissue and/or artificial polymers. The implantation of these scaffolds adds risks of pathogen transmission, undesirable inflammation, and other immunological reactions, as well as ethical issues in clinical practice. The current study was undertaken to evaluate the effectiveness of implanting autologous bone marrow mesenchymal stem cell-derived extracellular matrix (aBMSC-dECM) scaffolds after BMS for cartilage repair.

METHODS

Full osteochondral defects were performed on the trochlear groove of both knees in 24 rabbits. One group underwent BMS only in the right knee (the BMS group), and the other group was treated by implantation of the aBMSC-dECM scaffold after BMS in the left knee (the aBMSC-dECM scaffold group).

RESULTS

Better repair of cartilage defects was observed in the aBMSC-dECM scaffold group than in the BMS group according to gross observation, histological assessments, immunohistochemistry, and chemical assay. The glycosaminoglycan and DNA content, the distribution of proteoglycan, and the distribution and arrangement of type II and I collagen fibers in the repaired tissue in the aBMSC-dECM scaffold group at 12 weeks after surgery were similar to that surrounding normal hyaline cartilage.

CONCLUSIONS

Implanting aBMSC-dECM scaffolds can enhance the therapeutic effect of BMS on articular cartilage repair, and this combination treatment is a potential method for successful articular cartilage repair.

Histomorphochemical comparison of microfracture as a first-line and a salvage procedure: is microfracture still a viable option for knee cartilage repair in a salvage situation?

Microfracture is considered as the first-line procedure for knee cartilage repair, but the results of microfracture seem less predictable and rather controversial in a salvage situation. Thus, the purpose of the study was to histomorphochemically compare microfracture as a salvage procedure with microfracture as a first-line procedure in a rabbit model. We hypothesized that microfracture in a salvage situation would result in histomorphochemically inferior cartilage repair compared to microfracture as a first-line procedure, and the inferiority would be attributed to less migration of reparable marrow cells to the defect due to destruction of microarchitecture of the subchondral bone. Thirty-six New Zealand white rabbits were divided into three groups: (i) untreated full-thickness chondral defect, (ii) single microfracture treatment (first microfracture group), and (iii) repeated microfracture in 8 weeks after the first procedure (second microfracture group). In each group, rabbits were sacrificed at the end of 8 weeks, and osteochondral specimens at the repair sites were obtained for histomorphochemical analysis. Results showed that microfracture as a salvage procedure resulted in overall inferior cartilage repair histomorphochemically compared with microfracture as a first-line procedure, which correlated with deteriorative changes in the quality of underlying subchondral bone rather than intrinsic incapability to recruit the reparative cells in the defect area. In conclusion, although a comparable number of reparable cells and a mechanically weakened subchondral bone are anticipated, more study is necessary to clearly determine when a microfracture should be performed in a situation.

Effects of low-intensity ultrasound on gramicidin D-induced erythrocyte edema

OBJECTIVES

To determine whether low-intensity ultrasound (US) can reduce red blood cell (RBC) edema and, if so, whether the US activity is associated with aquaporin 1 (AQP-1), a water channel in the cell membrane.

METHODS

Red blood cell edema was induced by gramicidin D treatment at 40 ng/mL for 20 minutes and evaluated by a hematocrit assay. Low-intensity continuous wave US at 1 MHz was applied to RBCs for the last 10 minutes of gramicidin D treatment. To determine whether US activity was associated with AQP-1, RBCs were treated with 40 μM mercuric chloride (HgCl(2)), an AQP-1 inhibitor, for 20 minutes at the time of gramicidin D treatment. Posttreatment morphologic changes in RBCs were observed by actin staining with phalloidin.

RESULTS

Red blood cell edema increased significantly with gramicidin D at 20 (1.8%), 40 (6.7%), 60 (16.7%), and 80 (11.3%) ng/mL, reaching a peak at 60 ng/mL, compared to the control group (20 ng/mL, P = .019; 40, 60, and 80 ng/mL, P < .001). No significant RBC hemolysis was observed in any group. Edema induced by gramicidin D at 40 ng/mL was significantly reduced by US at 30 (3.4%; P = .003), 70 (4.4%; P = .001), and 100 (2.9%; P = .001) mW/cm(2). Subsequent experiments showed that edema reduction by US ranged from 7% to 10%. Cotreatment with HgCl(2) partially reversed the US effect and showed a significantly different level of edema compared to gramicidin D-alone and US-cotreated groups (P = .001). These results were confirmed by microscopic observation of RBC morphologic changes.

CONCLUSIONS

Low-intensity US could reduce gramicidin D-induced RBC edema, and its effect appeared to at least partly involve regulation of AQP-1 activity. These results suggest that low-intensity US can be used as an alternative treatment to control edema and related disorders.

Cartilage extra-cellular matrix biomembrane for the enhancement of microfractured defects

PURPOSE

The purpose of the study was to evaluate whether the biomembrane made of cartilage extracellular matrix, designed to provide cartilage-like favourable environments as well as to prevent against washout of blood clot after microfracture, would enhance cartilage repair compared with the conventional microfracture technique.

METHODS

A prospective trial was designed to compare the biomembrane cover after microfracture with conventional microfracture among patients with grade III-IV symptomatic cartilage defect in the knee joint. Patients aged 18-60 years were assigned to either the microfracture/biomembrane (n = 45) or microfracture groups (n = 19). Among them, 24 knees in the microfracture/biomembrane and 12 knees in the microfracture were followed up for 2 years. Cartilage repair was assessed with magnetic resonance imagings taken 6 months, 1 year, and 2 years postoperatively, and the clinical outcomes were also recorded.

RESULTS

Compared with conventional microfracture, microfracture/biomembrane resulted in greater degree of cartilage repair (p = 0.043). In the intra-group analysis, while microfracture showed moderate to good degree of cartilage repair in nearly 50 % of the patients (47 % at 6 months to 50% at 2 years; n.s.), microfracture/biomembrane maintained an equivalent degree of repair up to 2 years (88% at 6 months to 75% at 2 years; n.s.). The clinical outcome at 2 years also showed improved knee score and satisfaction and decreased pain in each group, but the difference between the two groups was not statistically significant.

CONCLUSIONS

Compared with conventional microfracture, biomembrane cover after microfracture yielded superior outcome in terms of the degree of cartilage repair during 2 years of follow-up. This implies that initial protection of blood clot and immature repair tissue at the microfractured defect is important for the promotion of enhanced cartilage repair, which may be obtained by the application of a biomembrane.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.

Superconducting properties of hole doped Ba(0.6)Li(0.4)Fe2As2 single crystal

We report the emergence of superconductivity in Li doped Ba-122 single crystals grown by the Bridgman method. The superconducting transition temperature Tc,onset is around 19 K. The specific heat capacity C/T shows a weak anomaly near Tc. The value of ΔC/γnTc is smaller than the value predicted in BCS theory indicating a multigap nature of the sample. The magnetic measurements show that the lower critical field Hc1(T) exhibits a linear temperature dependence, with a pronounced change of the Hc1(T) curvature around 0.4Tc and Hc1(0) ≈ 430 Oe in the Ba0.6Li0.4Fe2As2 single crystal. Furthermore, temperature dependence of the penetration depth λ(T) follows a power law (~T(n)) below 0.4Tc which predicts possible S±-wave pairing in a Ba0.6Li0.4Fe2As2 superconductor. Over a wide range of temperatures, the Jc(H) exhibits a relation J(c)[proportionality] H(-α) with α = 0.5 ~ 0.6 for H || c and H || ab which indicates random defects in the sample. We found that the temperature dependence of the critical current density Jc(T) can be fitted well with the δl-type pinning model, whose origin is attributed to spatial variations of charge carrier mean free path l. We suggest that the large mismatch in the ionic radius of Ba and Li can affect the irreversible magnetic properties of the Ba0.6Li0.4Fe2As2 single crystal without any structural transition.

Inhibition of blood vessel formation by a chondrocyte-derived extracellular matrix

In this study, the chondrocyte-derived extracellular matrix (CECM) was evaluated for its activity to inhibit vessel invasion in vitro and in vivo. Human umbilical vein endothelial cells (HUVECs) and rabbit chondrocytes were plated on a bio-membrane made of CECM or human amniotic membrane (HAM). The adhesion, proliferation, and tube formation activity of HUVECs and chondrocytes were examined. The CECM and HAM powders were then mixed individually in Matrigel and injected subcutaneously into nude mice to examine vessel invasion in vivo after 1 week. Finally, a rabbit model of corneal neovascularization (NV) was induced by 3-point sutures in the upper cornea, and CECM and HAM membranes were implanted onto the corneal surface at day 5 after suture injury. The rabbits were sacrificed at 7 days after transplantation and the histopathological analysis was performed. The adhesion and proliferation of HUVECs were more efficient on the HAM than on the CECM membrane. However, chondrocytes on each membrane showed an opposite result being more efficient on the CECM membrane. The vessel invasion in vivo also occurred more deeply and intensively in Matrigel containing HAM than in the one containing CECM. In the rabbit NV model, CECM efficiently inhibited the neovessels formation and histological remodeling in the injured cornea. In summary, our findings suggest that CECM, an integral cartilage ECM composite, shows an inhibitory effect on vessel invasion both in vitro and in vivo, and could be a useful tool in a variety of biological and therapeutic applications including the prevention of neovascularization after cornea injury.

Tissue-engineered tracheal reconstruction using chondrocyte seeded on a porcine cartilage-derived substance scaffold

OBJECTIVES

Tracheal reconstruction with tissue-engineering technique has come into the limelight in the realm of head and neck surgery. We intended to evaluate the plausibility of allogenic chondrocytes cultured with porcine cartilage-derived substance (PCS) scaffold for partial tracheal defect reconstruction.

METHODS

Powder made from crushed and decellularized porcine articular cartilage was formed as 5 mm × 12 mm (height × diameter) scaffold. Chondrocytes from rabbit articular cartilage were expanded and cultured with PCS scaffold. After 7 weeks culture, the scaffolds were implanted on a 5 mm × 10 mm artificial tracheal defect in six rabbits. Two, four and eight weeks postoperatively, the sites were evaluated endoscopically, radiologically, histologically and functionally.

RESULTS

None of the six rabbits showed any sign of respiratory distress. Endoscopic examination did not show any collapse or blockage of the reconstructed trachea and the defects were completely covered with regenerated respiratory epithelium. Computed tomography showed good luminal contour of trachea. Postoperative histologic data showed that the implanted chondrocyte successfully formed neo-cartilage with minimal inflammatory response and granulation tissue. Ciliary beat frequency of regenerated epithelium was similar to those of normal adjacent mucosa.

CONCLUSIONS

The shape and function of reconstructed trachea using allogenic chondrocytes cultured with PCS scaffold was restored successfully without any graft rejection.

Feasibility of autologous bone marrow mesenchymal stem cell-derived extracellular matrix scaffold for cartilage tissue engineering

Extracellular matrix (ECM) materials are widely used in cartilage tissue engineering. However, the current ECM materials are unsatisfactory for clinical practice as most of them are derived from allogenous or xenogenous tissue. This study was designed to develop a novel autologous ECM scaffold for cartilage tissue engineering. The autologous bone marrow mesenchymal stem cell-derived ECM (aBMSC-dECM) membrane was collected and fabricated into a three-dimensional porous scaffold via cross-linking and freeze-drying techniques. Articular chondrocytes were seeded into the aBMSC-dECM scaffold and atelocollagen scaffold, respectively. An in vitro culture and an in vivo implantation in nude mice model were performed to evaluate the influence on engineered cartilage. The current results showed that the aBMSC-dECM scaffold had a good microstructure and biocompatibility. After 4 weeks in vitro culture, the engineered cartilage in the aBMSC-dECM scaffold group formed thicker cartilage tissue with more homogeneous structure and higher expressions of cartilaginous gene and protein compared with the atelocollagen scaffold group. Furthermore, the engineered cartilage based on the aBMSC-dECM scaffold showed better cartilage formation in terms of volume and homogeneity, cartilage matrix content, and compressive modulus after 3 weeks in vivo implantation. These results indicated that the aBMSC-dECM scaffold could be a successful novel candidate scaffold for cartilage tissue engineering.

Effect of different bone marrow stimulation techniques (BSTs) on MSCs mobilization

The therapeutic effect of bone marrow stimulation techniques (BSTs) is mainly attributed to the role of mesenchymal stem cells (MSCs) from the bone marrow. However, no studies have directly shown the amount of MSCs drained by BSTs. This study hypothesized that differences in the opening of subchondral bone affect the number of MSCs drained from the bone marrow. We purposed that as the exposed area and hole size of BSTs vary, the number of MSCs drained out was measured. Three groups of different BSTs were designed that have variations in the sizes of total exposed area and individual holes. Three different BSTs using a curette, 1.5- and 0.8-mm awls were carried out on the full-thickness femoral cartilage defect of young rabbits. After BST, the number of MSCs in the blood clot was measured by CFU-Fs assay. As the size of the total exposed area increased, so did the number of MSCs obtained. The number of MSCs drained from bone marrow may vary depending on different BSTs and this could affect therapeutic efficacy of cartilage defect. As current microfracture (MF) method cannot drain the most MSCs clinically, more improved surgery technique is needed.

Construction of a tissue-engineered annulus fibrosus

The intervertebral disc is composed of load-bearing fibrocartilage that may be subjected to compressive forces up to 10 times the body weight. The multilaminated outer layer, the annulus fibrosus (AF), is vulnerable to damage and its regenerative potential is limited, sometimes leading to nuclear herniation. Scaffold-based tissue engineering of AF using stem cell technology has enabled the development of bi-laminate constructs after 10 weeks of culture. It is difficult to know if these constructs are limited by the differentiation state of the stem cells or the culture system. In this study, we have characterized an expandable scaffold-free neoconstruct using autologous AF cells. The construct was prepared from pellet cultures derived from monolayer cultures of AF cells from mature pigs that became embedded in their own extracellular matrix. The pellet cultures were incubated for 24 h in a standardized conical tube and then carefully transferred intact to a culture flask and incubated for 21 days to allow continued matrix synthesis. Cell viability was maintained above 90% throughout the culture period. The engineered scaffold-free construct was compared with the native AF tissue by characterization of gene expression of representative markers, histological architecture, and biochemical composition. The morphological and biochemical characteristics of the cultured disc construct are very similar to that of native AF. The cell number per gram of construct was equal to that of native AF. Expression of aggrecan was elevated in the engineered construct compared with RNA extracted from the AF. The glycosaminoglycan content in the engineered construct showed no significant difference to that from native construct. These data indicate that scaffold-free tissue constructs prepared from AF cells using a pellet-culture format may be useful for in vitro expansion for transplantation into damaged discs.

Mechanical stimulation by ultrasound enhances chondrogenic differentiation of mesenchymal stem cells in a fibrin-hyaluronic acid hydrogel

Chondrogenic differentiation and cartilage tissue formation derived from stem cells are highly dependent on both biological and mechanical factors. This study investigated whether or not fibrin-hyaluronic acid (HA) coupled with low-intensity ultrasound (LIUS), a mechanical stimulation, produces an additive or synergistic effect on the chondrogenesis of rabbit mesenchymal stem cells (MSCs) derived from bone marrow. For the purpose of comparison, rabbit MSCs were first cultured in fibrin-HA or alginate hydrogels, and then subjected to chondrogenic differentiation in chondrogenic-defined medium for 4 weeks in the presence of either transforming growth factor-beta3 (TGF-β3) (10 ng/mL) or LIUS treatment (1.0 MHz and 200 mW/cm(2) ). The resulting samples were evaluated at 1 and 4 weeks by histological observation, chemical assays, and mechanical analysis. The fibrin-HA hydrogel was found to be more efficient than alginate in promoting chondrogenesis of the MSCs by producing a larger amount of sulfated glycosaminoglycans (GAGs) and collagen, and engineered constructs made with the hydrogel demonstrated higher mechanical strength. At 4 weeks of tissue culture, the chondrogenesis of the MSCs in fibrin-HA were shown to be further enhanced by treatment with LIUS, as observed by analyses for the amounts of GAGs and collagen, and mechanical strength testing. In contrast, TGF-β3, a well-known chondrogenic inducer, showed a marginal additive effect in the amount of collagen only. These results revealed that LIUS further enhanced chondrogenesis of the MSCs cultured in fibrin-HA, in vitro, and suggested that the combination of fibrin-HA and LIUS is a useful tool in constructing high-quality cartilage tissues from MSCs.

An electrostatically crosslinked chitosan hydrogel as a drug carrier

Considerable efforts have been devoted to control and maintain the sustained release of proteins. In this experiment, we used bovine serum albumin-fluorescein isothiocyanate (BSA-FITC) as a model protein to explore the potential utility of a chitosan and glycerol phosphate disodium salt (GP) hydrogel as a protein drug depot. The mixing of chitosan and GP solutions (0, 10, 20 and 30 wt%) formed a liquid at room temperature. At 37 °C, however, the chitosan/GP solutions formed hydrogels through an electrostatic crosslinking process. This electrostatic interaction between the chitosan, cationic amine group, and GP, anionic phosphate group, was confirmed by the changes of zeta potentials and particle sizes of this solution. The electrostatic interaction depended both on the GP ratios in chitosan and the incubation time of chitosan/GP solutions. Furthermore, BSA-FITC-loaded chitosan/GP hydrogels were examined for their ability as potential depots for the BSA drugs. Hence, when observed, the BSA-FITC-loaded chitosan/GP hydrogels showed an in vitro sustained release profile of BSA up to 14 days. Collectively, our results show that the chitosan/GP hydrogels described here, can serve as depots for BSA drugs.

Chip-based comparison of the osteogenesis of human bone marrow- and adipose tissue-derived mesenchymal stem cells under mechanical stimulation

Adipose tissue-derived stem cells (ASCs) are considered as an attractive stem cell source for tissue engineering and regenerative medicine. We compared human bone marrow-derived mesenchymal stem cells (hMSCs) and hASCs under dynamic hydraulic compression to evaluate and compare osteogenic abilities. A novel micro cell chip integrated with microvalves and microscale cell culture chambers separated from an air-pressure chamber was developed using microfabrication technology. The microscale chip enables the culture of two types of stem cells concurrently, where each is loaded into cell culture chambers and dynamic compressive stimulation is applied to the cells uniformly. Dynamic hydraulic compression (1 Hz, 1 psi) increased the production of osteogenic matrix components (bone sialoprotein, oateopontin, type I collagen) and integrin (CD11b and CD31) expression from both stem cell sources. Alkaline phosphatase and Alrizarin red staining were evident in the stimulated hMSCs, while the stimulated hASCs did not show significant increases in staining under the same stimulation conditions. Upon application of mechanical stimulus to the two types of stem cells, integrin (β1) and osteogenic gene markers were upregulated from both cell types. In conclusion, stimulated hMSCs and hASCs showed increased osteogenic gene expression compared to non-stimulated groups. The hMSCs were more sensitive to mechanical stimulation and more effective towards osteogenic differentiation than the hASCs under these modes of mechanical stimulation.