Search

Engineering living bone tissue of defined shape on-demand has remained a challenge. 3D-bioprinting (3DBP), a biofabrication process capable of yielding cell constructs of defined shape, when combined with developmental engineering can provide a possible path forward. Through the development of a bioink possessing appropriate rheological properties to carry a high cell load and concurrently yield physically stable structures, printing of stable, cell-laden, single-matrix constructs of anatomical shapes was realized without the need for fugitive or support phases. Using this bioink system, constructs of hypertrophic cartilage of predesigned geometry were engineered in vitro by printing human MSCs at a high density to drive spontaneous condensation and implanted in nude mice to evoke endochondral ossification. The implanted constructs retained their prescribed shape over a 12-week period and underwent remodeling to yield ossicles of the designed shape with neovascularization. Micro-CT, histological and immunohistochemistry assessments confirmed bone tissue characteristics and the presence of human cells. These results demonstrate the potential of 3DBP to fabricate complex bone tissue for clinical application. This article is protected by copyright. All rights reserved.

Engineering living bone tissue of defined shape on-demand has remained a challenge. 3D-bioprinting (3DBP), a biofabrication process capable of yielding cell constructs of defined shape, when combined with developmental engineering can provide a possible path forward. Through the development of a bioink possessing appropriate rheological properties to carry a high cell load and concurrently yield physically stable structures, printing of stable, cell-laden, single-matrix constructs of anatomical shapes was realized without the need for fugitive or support phases. Using this bioink system, constructs of hypertrophic cartilage of predesigned geometry were engineered in vitro by printing human MSCs at a high density to drive spontaneous condensation and implanted in nude mice to evoke endochondral ossification. The implanted constructs retained their prescribed shape over a 12-week period and underwent remodeling to yield ossicles of the designed shape with neovascularization. Micro-CT, histological and immunohistochemistry assessments confirmed bone tissue characteristics and the presence of human cells. These results demonstrate the potential of 3DBP to fabricate complex bone tissue for clinical application.

Joint tissues consist of trabecular and cortical bone as well as calcified and hyaline cartilage, which presents a challenge for hard X-ray-based visualization on the sub-cellular level due to the wide range of local X-ray absorption values. The density of the calcified tissues requires rather high photon energy, which often leads to insufficient contrast within the cartilage and impedes the visualization of individual biological cells. Decalcification of the tissues reduces the total and local X-ray absorption values and allows for selecting a lower photon energy. Further contrast enhancement can be achieved by ethanol fixation and paraffin tissue embedding. In this study, we (i) searched for an appropriate visualization method to investigate lesions generated by a laser osteotome and (ii) visualized a decalcified porcine joint after ethanol fixation and subsequent paraffin embedding using laboratory- and synchrotron radiation-based microtomography. The experiments at the ANATOMIX beamline of Synchrotron SOLEIL were performed in off-axis scan mode with a pixel size of 1.3 um. Individual cells in all layers of the joint could be made visible and the effect of ethanol fixation and paraffin embedding demonstrated., Comment: 10 pages. Event: SPIE Optical Engineering + Applications, 2022, San Diego, California, United States

Objective Cellular and molecular events occurring in cartilage regions close to injury are poorly investigated, but can possibly compromise the outcome of cell-based cartilage repair. In this study, key functional properties were assessed for cartilage biopsies collected from the central part of traumatic joint lesions ( central) and from regions surrounding the defect ( peripheral). These properties were then correlated with the quality of the initial cartilage biopsy and the inflammatory state of the joint. Design Cartilage samples were collected from knee joints of 42 patients with traumatic knee injuries and analyzed for cell phenotype (by reverse transcriptas-polymerase chain reaction), histological quality, cellularity, cell viability, proliferation capacity, and post-expansion chondrogenic capacity of chondrocytes (in pellet culture). Synovium was also harvested and analyzed for the expression of inflammatory cytokines. Results Cartilage quality and post-expansion chondrogenic capacity were higher in peripheral versus central samples. Differences between these 2 parameters were more pronounced in joints with high inflammatory features characterized by >100-fold difference in the mRNA levels of IL6 and IL8 in the corresponding synovium. Peripheral chondrocytes isolated from good- versus bad-quality biopsies expressed higher levels of collagen II/I and aggrecan/versican and lower levels of MMP13 and ADAMTS5. They also exhibited reduced proliferation and enhanced cartilage-forming capacity. Conclusions Chondrocytes at the periphery of traumatic lesions better maintain properties of healthy cartilage compared to those isolated from the center, even when derived from bad-quality tissues harvested from highly inflamed joints. Future studies are necessary to investigate the change of functional properties of peripheral chondrocytes over time.

Background. It is generally assumed that traumatic cartilage lesions affect the whole joint homeostasis. However, it remains unknown to which extent the properties of chondrocytes within lesions are affected compared to cells from adjacent locations. To unravel cellular and molecular events occurring in cartilage regions close to injury sites, we collected cartilage biopsies from the central part of the lesions ( central ) and from regions closely surrounding the lesion ( peripheral , 2-5mm distance from defect) of traumatic joints and assessed their key functional properties. Additionally, we investigated the correlation of these properties with the inflammatory features of the joint and the quality of the initial cartilage biopsy. Methods. Cartilage samples were collected from the knee joints of 42 patients (male:female = 7:3, age range: 18-60y) with traumatic knee injuries and analysed for cell phenotype (by RT-PCR), histological quality (using a grading score based on glycosaminoglycan staining), cellularity (cell numbers/gram tissue, isolated after enzymatic digestion), cell viability, proliferation capacity (cell doublings/day) and post-expansion chondrogenic capacity of chondrocytes (Bern score of chondrogenically cultured cells in pellets). In addition, synovial tissues were harvested and analysed for the expression of inflammatory cytokine genes. Results. Cartilage quality and post-expansion chondrogenic capacity were higher in peripheral vs central samples. Differences between these two parameters were more pronounced in joints with high (vs low) inflammatory features, as characterised by >100-fold difference in the mRNA levels of IL-6 and IL-8 in the corresponding synovial tissues. Peripheral chondrocytes isolated from initially good compared to bad quality biopsies expressed higher levels of chondrogenic markers (type II/I collagen and aggrecan/versican ratios) and lower levels of cartilage degrading markers MMP13 and ADAMTS5. They also exhibited reduced proliferation and enhanced cartilage-forming capacity. Conclusions. Chondrocytes at the periphery of traumatic lesions better maintain properties typical of healthy cartilage as compared to those isolated from central parts even when derived from bad quality tissues harvested from highly inflamed joints. Future studies will be necessary to investigate the change of functional properties of peripheral chondrocytes over time and, consequently, to identify a “point of no return” (since onset of symptoms) for a possible use of such chondrocytes in cartilage repair strategies.

OBJECTIVE Implantation of autologous chondrocytes for cartilage repair requires harvesting of undamaged cartilage, implying an additional joint arthroscopy surgery and further damage to the articular surface. As alternative possible cell sources, in this study we assessed the proliferation and chondrogenic capacity of debrided Knee Chondrocytes (dKC) and Nasal Chondrocytes (NC) collected from the same patients. METHODS Matched NC and dKC pairs from 13 patients enrolled in two clinical studies (NCT01605201 and NCT026739059) were expanded in monolayer and then chondro-differentiated in 3D collagenous scaffolds in medium with or without Transforming Growth Factor beta 1 (TGFβ1). Cell proliferation and amount of cartilage matrix production by these two cell types were assessed. RESULTS dKC exhibited an inferior proliferation rate than NC, and a lower capacity to chondro-differentiate. Resulting dKC-grafts contained lower amounts of cartilage specific matrix components glycosaminoglycans and type II collagen. The cartilage forming capacity of dKC did not significantly correlate with specific clinical parameters and was only partially improved by medium supplemention with TGFβ1. CONCLUSIONS dKC exhibit a reproducibly poor capacity to engineer cartilage grafts. Our in vitro data suggest that NC would be a better suitable cell source for the generation of autologous cartilage grafts.

Background: Anterior shoulder instability is a debilitating condition that can require stabilization via a Latarjet procedure. Purpose: The aim of this study was to characterize the histological composition of the articular-sided surface of the coracoid bone graft after Latarjet procedure. Specific features of cells isolated from the coracoid and graft tissues were assessed. Study Design: Case series; Level of evidence, 4. Methods: Tissue samples were harvested from 9 consecutive patients undergoing arthroscopic debridement and screw removal after arthroscopic or open Latarjet procedure. Tissues were processed histologically. In 2 patients, the samples were analyzed to assess specific cellular properties. Results: Safranin O staining indicated that glenoid tissues contained variable amounts of glycosaminoglycan (GAG) and round chondrocytic cells mainly organized in clusters. Graft tissues contained less GAG and were more cellular but were not organized in clusters and had variable morphological features. An association appeared to exist between the cartilage quality of glenoid tissues and that of the graft tissues. Cells isolated from glenoid and graft tissues exhibited similar proliferation capacity. Conclusion: The results of our analysis show that cells located at the articular-sided surface of transferred coracoid grafts demonstrate fibrocartilaginous properties and may have the capacity for chondral proliferation. Further studies are needed to confirm this observation and future application.

Summary Background Articular cartilage injuries have poor repair capacity, leading to progressive joint damage, and cannot be restored predictably by either conventional treatments or advanced therapies based on implantation of articular chondrocytes. Compared with articular chondrocytes, chondrocytes derived from the nasal septum have superior and more reproducible capacity to generate hyaline-like cartilage tissues, with the plasticity to adapt to a joint environment. We aimed to assess whether engineered autologous nasal chondrocyte-based cartilage grafts allow safe and functional restoration of knee cartilage defects. Methods In a first-in-human trial, ten patients with symptomatic, post-traumatic, full-thickness cartilage lesions (2–6 cm 2 ) on the femoral condyle or trochlea were treated at University Hospital Basel in Switzerland. Chondrocytes isolated from a 6 mm nasal septum biopsy specimen were expanded and cultured onto collagen membranes to engineer cartilage grafts (30 × 40 × 2 mm). The engineered tissues were implanted into the femoral defects via mini-arthrotomy and assessed up to 24 months after surgery. Primary outcomes were feasibility and safety of the procedure. Secondary outcomes included self-assessed clinical scores and MRI-based estimation of morphological and compositional quality of the repair tissue. This study is registered with ClinicalTrials.gov, number NCT01605201. The study is ongoing, with an approved extension to 25 patients. Findings For every patient, it was feasible to manufacture cartilaginous grafts with nasal chondrocytes embedded in an extracellular matrix rich in glycosaminoglycan and type II collagen. Engineered tissues were stable through handling with forceps and could be secured in the injured joints. No adverse reactions were recorded and self-assessed clinical scores for pain, knee function, and quality of life were improved significantly from before surgery to 24 months after surgery. Radiological assessments indicated variable degrees of defect filling and development of repair tissue approaching the composition of native cartilage. Interpretation Hyaline-like cartilage tissues, engineered from autologous nasal chondrocytes, can be used clinically for repair of articular cartilage defects in the knee. Future studies are warranted to assess efficacy in large controlled trials and to investigate an extension of indications to early degenerative states or to other joints. Funding Deutsche Arthrose-Hilfe.

Summary Background Autologous native cartilage from the nasal septum, ear, or rib is the standard material for surgical reconstruction of the nasal alar lobule after two-layer excision of non-melanoma skin cancer. We assessed whether engineered autologous cartilage grafts allow safe and functional alar lobule restoration. Methods In a first-in-human trial, we recruited five patients at the University Hospital Basel (Basel, Switzerland). To be eligible, patients had to be aged at least 18 years and have a two-layer defect (≥50% size of alar subunit) after excision of non-melanoma skin cancer on the alar lobule. Chondrocytes (isolated from a 6 mm cartilage biopsy sample from the nasal septum harvested under local anaesthesia during collection of tumour biopsy sample) were expanded, seeded, and cultured with autologous serum onto collagen type I and type III membranes in the course of 4 weeks. The resulting engineered cartilage grafts (25 mm × 25 mm × 2 mm) were shaped intra-operatively and implanted after tumour excision under paramedian forehead or nasolabial flaps, as in standard reconstruction with native cartilage. During flap refinement after 6 months, we took biopsy samples of repair tissues and histologically analysed them. The primary outcomes were safety and feasibility of the procedure, assessed 12 months after reconstruction. At least 1 year after implantation, when reconstruction is typically stabilised, we assessed patient satisfaction and functional outcomes (alar cutaneous sensibility, structural stability, and respiratory flow rate). Findings Between Dec 13, 2010, and Feb 6, 2012, we enrolled two women and three men aged 76–88 years. All engineered grafts contained a mixed hyaline and fibrous cartilage matrix. 6 months after implantation, reconstructed tissues displayed fibromuscular fatty structures typical of the alar lobule. After 1 year, all patients were satisfied with the aesthetic and functional outcomes and no adverse events had been recorded. Cutaneous sensibility and structural stability of the reconstructed area were clinically satisfactory, with adequate respiratory function. Interpretation Autologous nasal cartilage tissues can be engineered and clinically used for functional restoration of alar lobules. Engineered cartilage should now be assessed for other challenging facial reconstructions. Funding Foundation of the Department of Surgery, University Hospital Basel; and Krebsliga beider Basel.

Summary Objective To characterize the post-expansion cartilage-forming capacity of chondrocytes harvested from detached fragments of osteochondral lesions (OCLs) of ankle joints (Damaged Ankle Cartilage Fragments, DACF), with normal ankle cartilage (NAC) as control. Design DACF were obtained from six patients (mean age: 35years) with symptomatic OCLs of the talus, while NAC were from 10 autopsies (mean age: 55 years). Isolated chondrocytes were expanded for two passages and then cultured in pellets for 14 days or onto HYAFF ® -11 meshes (FAB, Italy) for up to 28 days. Resulting tissues were assessed histologically, biochemically [glycosaminoglycan (GAG), DNA and type II collagen (CII)] and biomechanically. Results As compared to NAC, DACF contained significantly lower amounts of DNA (3.0-fold), GAG (5.3-fold) and CII (1.5-fold) and higher amounts of type I collagen (6.2-fold). Following 14 days of culture in pellets, DACF-chondrocytes generated tissues less intensely stained for Safranin-O and CII, with significantly lower GAG contents (2.8-fold). After 28 days of culture onto HYAFF ® -11, tissues generated by DACF-chondrocytes were less intensely stained for Safranin-O and CII, contained significantly lower amounts of GAG (1.9-fold) and CII (1.4-fold) and had lower equilibrium (1.7-fold) and dynamic pulsatile modulus (3.3-fold) than NAC-chondrocytes. Conclusion We demonstrated that DACF-chondrocytes have inferior cartilage-forming capacity as compared to NAC-chondrocytes, possibly resulting from environmental changes associated with trauma/disease. The study opens some reservations on the use of DACF-derived cells for the repair of ankle cartilage defects, especially in the context of tissue engineering-based approaches.

The use of fetal bovine serum (FBS) as a culture medium supplement in cell therapy and clinical tissue engineering is challenged by immunological concerns and the risk of disease transmission. Here we tested whether human, thrombin-activated, pooled, platelet-rich plasma (tPRP) can be substituted for FBS in the engineering of osteogenic and vasculogenic grafts, using cells from the stromal vascular fraction (SVF) of human adipose tissue. SVF cells were cultured under perfusion flow into porous hydroxyapatite scaffolds for 5 days, with the medium supplemented with either 10% tPRP or 10% FBS and implanted in an ectopic mouse model. Following in vitro culture, as compared to FBS, the use of tPRP did not modify the fraction of clonogenic cells or the different cell phenotypes, but increased by 1.9-fold the total number of cells. After 8 weeks in vivo, bone tissue was formed more reproducibly and in higher amounts (3.7-fold increase) in constructs cultured with tPRP. Staining for human-specific ALU sequences and for the human isoforms of CD31/CD34 revealed the human origin of the bone, the formation of blood vessels by human vascular progenitors and a higher density of human cells in implants cultured with tPRP. In summary, tPRP supports higher efficiency of bone formation by SVF cells than FBS, likely by enhancing cell expansion in vitro while maintaining vasculogenic properties. The use of tPRP may facilitate the clinical translation of osteogenic grafts with intrinsic capacity for vascularization, based on the use of adipose-derived cells. Copyright © 2015 John Wiley & Sons, Ltd.

The use of fetal bovine serum (FBS) as a culture medium supplement in cell therapy and clinical tissue engineering is challenged by immunological concerns and the risk of disease transmission. Here we tested whether human, thrombin-activated, pooled, platelet-rich plasma (tPRP) can be substituted for FBS in the engineering of osteogenic and vasculogenic grafts, using cells from the stromal vascular fraction (SVF) of human adipose tissue. SVF cells were cultured under perfusion flow into porous hydroxyapatite scaffolds for 5 days, with the medium supplemented with either 10% tPRP or 10% FBS and implanted in an ectopic mouse model. Following in vitro culture, as compared to FBS, the use of tPRP did not modify the fraction of clonogenic cells or the different cell phenotypes, but increased by 1.9-fold the total number of cells. After 8 weeks in vivo, bone tissue was formed more reproducibly and in higher amounts (3.7-fold increase) in constructs cultured with tPRP. Staining for human-specific ALU sequences and for the human isoforms of CD31/CD34 revealed the human origin of the bone, the formation of blood vessels by human vascular progenitors and a higher density of human cells in implants cultured with tPRP. In summary, tPRP supports higher efficiency of bone formation by SVF cells than FBS, likely by enhancing cell expansion in vitro while maintaining vasculogenic properties. The use of tPRP may facilitate the clinical translation of osteogenic grafts with intrinsic capacity for vascularization, based on the use of adipose-derived cells. Copyright © 2015 John WileySons, Ltd.

In the present study, the levels of soluble adhesion molecules P- and E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1) and of other markers of endothelial activation or injury, such as thrombomodulin, von Willebrand factor (vWF), as well as homocysteine, were prospectively investigated in 71 patients (21 women, 50 men, age 68+/-13) with predominantly femoropopliteal peripheral arterial occlusive disease (PAOD, stage II-IV, Fontaine) before and after percutaneous transluminal angioplasty (PTA). Thirty patients (42.3%) developed restenosis within 6 months, defined as a50% reduction of the lumen diameter at the site of PTA. At entry in the study, 46% and 58% of all patients had higher than normal levels of soluble P-selectin and VCAM-1, respectively. Thrombomodulin (P0.01) measured at entry, was significantly higher in patients who developed late restenosis, with trends for higher values for P-selectin, VCAM-1 and vWF. The relative risks for developing restenosis were 2.41 (CI95%: 1.23-4.75) and 1.54 (CI95%: 0.98-2.72) for thrombomodulin and P-selectin, respectively. Soluble P-selectin and the severity of PAOD (Fontaine stage III/IV) were found to be statistically indicative factors for late restenosis in a logistic regression risk factor analysis with an overall predictive value of 72%. At 6 months, those who developed restenosis had also higher soluble P-selectin (P0.01), VCAM-1 (P0.05) and a trend for higher thrombomodulin. Homocysteine was elevated in 52% of the patients at entry but neither was it associated with higher restenosis rates nor did it correlate with the levels of thrombomodulin or the other adhesion molecules. These findings indicate that patients with PAOD have to a significant proportion, elevated levels of circulating soluble adhesion molecules and markers of endothelial activation occurring in concert with an ongoing atherosclerotic process.

We revised a neonatal morbidity scale (the NMS) that has served as a means for comparison of neonatal illness in studies of high-risk neonates after initial hospital discharge. With an inception cohort approach, 89 premature infants at an urban university hospital were studied with the expanded scale (the ENMS). The original scale, published in 1983, was reworked and expanded based on advances in the diagnosis and management of neonates. A social risk scale was added. Linear and logistic regression analyses were used to judge validity of the newly revised scale and to examine its predictive ability for outcomes at six months of age. Concurrent validity was supported by the relationship between the ENMS-SRS and: birthweight (R2 = .54), gestational age (R2 = .50), length of stay (R2 = .47). Inter-rater reliability was .95. The ENMS, embodying a contemporary patient profile, is valid for a population of premature infants in a U.S. urban setting and has predictive validity for a few outcomes within six months of discharge from a special care unit.

Atomic force microscopy (AFM) has been proposed as a tool to evaluate the structural and mechanical properties of cartilage tissue. Here, we aimed at assessing whether AFM can be employed to quantify spatially resolved elastic response of tissue engineered cartilage (TEC) to short exposure to IL-1β, thus mimicking the initially inflammatory implantation site. TEC generated by 14 days of pellet-culture of expanded human chondrocytes was left untreated (ctr) or exposed to IL-1β for 3 days. TEC pellets were then cut in halves that were glued on a Petri dish. Profiles of elasticity were obtained by sampling with a nanometer sized, pyramidal indenting tip, with 200µm step resolution, the freshly exposed surfaces along selected directions. Replicate TECs were analyzed biochemically and histologically. GAG contents and elasticity of pellets decreased (1.4- and 2.6-fold, respectively, p

Previous studies showed that human nasal chondrocytes (HNC) exhibit higher proliferation and chondrogenic capacity as compared to human articular chondrocytes (HAC). To consider HNC as a relevant alternative cell source for the repair of articular cartilage defects it is necessary to test how these cells react when exposed to environmental factors typical of an injured joint. We thus aimed this study at investigating the responses of HNC and HAC to exposure to interleukin (IL)-1? and low oxygen. For this purpose HAC and HNC harvested from the same donors (N=5) were expanded in vitro and then cultured in pellets or collagen-based scaffolds at standard (19%) or low oxygen (5%) conditions. Resulting tissues were analyzed after a short (3 days) exposure to IL-1?, mimicking the initially inflammatory implantation site, or following a recovery time (1 or 2 weeks for pellets and scaffolds, respectively). After IL-1? treatment, constructs generated by both HAC and HNC displayed a transient loss of GAG (up to 21.8% and 36.8%, respectively) and, consistently, an increased production of metalloproteases (MMP)-1 and -13. Collagen type II and the cryptic fragment of aggrecan (DIPEN), both evaluated immunohistochemically, displayed a trend consistent with GAG and MMPs production. HNC-based constructs exhibited a more efficient recovery upon IL-1? withdrawal, resulting in a higher accumulation of GAG (up to 2.6-fold) compared to the corresponding HAC-based tissues. On the other hand, HAC displayed a positive response to low oxygen culture, while HNC were only slightly affected by oxygen percentage. Collectively, under the conditions tested mimicking the postsurgery articular environment, HNC retained a tissue-forming capacity, similar or even better than HAC. These results represent a step forward in validating HNC as a cell source for cartilage tissue engineering strategies.

In this study, we aimed at developing and validating a technique for the engineering of osteochondral grafts based on the biological bonding of a chondral layer with a bony scaffold by cell-laid extracellular matrix. Osteochondral composites were generated by combining collagen-based matrices (Chondro-Gide) containing human chondrocytes with devitalized spongiosa cylinders (Tutobone) using a fibrin gel (Tisseel). We demonstrate that separate pre-culture of the chondral layer for 3 days prior to the generation of the composite allows for (i) more efficient cartilaginous matrix accumulation than no pre-culture, as assessed histologically and biochemically, and (ii) superior biological bonding to the bony scaffold than 14 days of pre-culture, as assessed using a peel-off mechanical test, developed to measure integration of bilayered materials. The presence of the bony scaffold induced an upregulation in the infiltrated cells of the osteoblast-related gene bone sialoprotein, indicative of the establishment of a gradient of cell phenotypes, but did not affect per se the quality of the cartilaginous matrix in the chondral layer. The described strategy to generate osteochondral plugs is simple to be implemented and--since it is based on clinically compliant cells and materials--is amenable to be readily tested in the clinic.

In this study, we addressed whether Bone Sialoprotein (BSP) coating of various substrates could enhance the in vitro osteogenic differentiation and in vivo bone formation capacity of human Bone Marrow Stromal Cells (BMSC). Moreover, we tested whether synthetic polymer-based porous scaffolds, despite the absence of a mineral component, could support ectopic bone formation by human BMSC if coated with BSP. Adsorption of recombinant human BSP on tissue culture-treated polystyrene (TCTP), beta-tricalcium phosphate (Osteologic) or synthetic polymer (Polyactive) substrates was dose dependent, but did not consistently accelerate or enhance in vitro BMSC osteogenic differentiation, as assessed by the mRNA expression of osteoblast-related genes. Similarly, BSP coating of porous beta-tricalcium phosphate scaffolds (Skelite) did not improve the efficiency of bone tissue formation following loading with BMSC and ectopic implantation in nude mice. Finally, Polyactive foams seeded with BMSC did not form bone tissue in the same ectopic assay, even if coated with BSP. We conclude that BSP coating of a variety of substrates is not directly associated with an enhancement of osteoprogenitor cell differentiation in vitro or in vivo, and that presentation of BSP on polymeric materials is not sufficient to prime BMSC functional osteoblastic differentiation in vivo.

In this study, we first aimed at determining whether human articular chondrocytes (HAC) proliferate in aggregates in the presence of strong chondrocyte mitogens. We then investigated if the aggregated cells have an enhanced chondrogenic capacity as compared to cells cultured in monolayer. HAC from four donors were cultured in tissue culture dishes either untreated or coated with 1% agarose in the presence of TGFbeta-1, FGF-2 and PDGF-BB. Proliferation and stage of differentiation were assessed by measuring respectively DNA contents and type II collagen mRNA. Expanded cells were induced to differentiate in pellets or in Hyaff-11 meshes and the formed tissues were analysed biochemically for glycosaminoglycans (GAG) and DNA, and histologically by Safranin O staining. The amount of DNA in aggregate cultures increased significantly from day 2 to day 6 (by 3.2-fold), but did not further increase with additional culture time. Expression of type II collagen mRNA was about two orders of magnitude higher in aggregated HAC as compared to monolayer expanded cells. Pellets generated by aggregated HAC were generally more intensely stained for GAG than those generated by monolayer-expanded cells. Scaffolds seeded with aggregates accumulated more GAG (1.3-fold) than scaffolds seeded with monolayer expanded HAC. In conclusion, this study showed that HAC culture in aggregates does not support a relevant degree of expansion. However, aggregation of expanded HAC prior to loading into a porous scaffold enhances the quality of the resulting tissues and could thus be introduced as an intermediate culture phase in the manufacture of engineered cartilage grafts.

For the generation of cell-based therapeutic products, it would be preferable to avoid the use of animal-derived components. Our study thus aimed at investigating the possibility to replace foetal bovine serum (FBS) with autologous serum (AS) for the engineering of cartilage grafts using expanded human nasal chondrocytes (HNC). HNC isolated from 7 donors were expanded in medium containing 10% FBS or AS at different concentrations (2%, 5% and 10%) and cultured in pellets using serum-free medium or in Hyaff(R)-11 meshes using medium containing FBS or AS. Tissue forming capacity was assessed histologically (Safranin O), immunohistochemically (type II collagen) and biochemically (glycosaminoglycans -GAG- and DNA). Differences among experimental groups were assessed by Mann Whitney tests. HNC expanded under the different serum conditions proliferated at comparable rates and generated cartilaginous pellets with similar histological appearance and amounts of GAG. Tissues generated by HNC from different donors cultured in Hyaff(R)-11 had variable quality, but the accumulated GAG amounts were comparable among the different serum conditions. Staining intensity for collagen type II was consistent with GAG deposition. Among the different serum conditions tested, the use of 2% AS resulted in the lowest variability in the GAG contents of generated tissues. In conclusion, a low percentage of AS can replace FBS both during the expansion and differentiation of HNC and reduce the variability in the quality of the resulting engineered cartilage tissues.

Anticardiolipin antibodies (aCL) or lupus anticoagulants (LA) have been found to exert an inhibitory action upon the activation and function of protein C, a natural coagulation inhibitor. Recently an in vitro phenomenon called resistance to activated protein C (APC resistance) has been described as the most frequent cause of hereditary thrombophilia. In order to see whether a positive association of APC resistance with aCL exists we examined plasma of 162 consecutive outpatients referred for thrombophilia screening. Further, the IgG fraction was isolated from plasma of two aCL-positive and LA-negative patients and of two aCL-negative healthy subjects by means of protein A affinity chromatography. Each of these isolates was mixed with normal plasma, and the APC resistance was assayed; 25/162 (15.4%) patients had confirmed abnormal APC resistance. Only 1/25 (4.0%) APC resistance-positive patients and 11/137 (8.0%) APC resistance-negative patients had positive IgG- and/or IgM-aCL (p = 0.5, nonsignificant). In the in vitro test system the APC resistance ratio remained unaffected after addition of normal IgG or aCL-IgG fraction in the tested normal plasma and did not deviate from the range of buffer controls. These data do not suggest any association of aCL with abnormal APC resistance. aCL-IgG fractions from aCL-positive and LA-negative plasmas do not interfere with the APC resistance test system in vitro in low concentration.

Heat stress (HS) reduces the many sequelae of lipopolysaccharide (LPS)-induced endotoxemia. Without HS, endotoxins have been shown to induce a transcriptional down-regulation of hepatocyte transport proteins for bile acids and organic anions. We performed experiments in isolated perfused rat livers at various times after LPS administration with and without HS pretreatment to determine whether HS would correct deficient transport of bromosulfophthalein (BSP). Possible mechanisms involved were investigated in livers from intact animals. In isolated perfused livers, LPS injection reduced BSP excretion to 48% compared with saline-injected controls (P < 0.01). When HS was applied 2 hours prior to LPS, BSP excretion increased to 74% of controls (P < 0.05 vs LPS and controls). Expression of the basolateral (Oatp1a1) and canalicular (Mrp2) organic anion transporter involved in the transport of BSP recovered more rapidly when HS preceded LPS application. Recovery of mRNA levels of these transporters occurred also earlier. Coimmunoprecipitation experiments and immunoelectron microscopy using a double immunogold labeling of heat shock protein 70 (HSP70) and various hepatocyte transporters suggested colocalization with HSP70 for the canalicular bile acid transporter (Bsep) in the subcanalicular space. In contrast, no colocalization was shown for Ntcp and anion transporters. In conclusion, we could show that HS enhances recovery of organic anion transporters and bile acid transporters following endotoxemia. Faster recovery of mRNA seems to be a key mechanism for anion transporters, whereas physical interaction with HSP70 plays a role in preservation of bile acid transporters. This interaction of HSP70 and canalicular transporters occurs only in pericanalicular vesicles but not when the protein is integrated into the plasma membrane.