ICRS 2019 - Conference Calendar

Browsing Over 343 Presentations

Podium Presentation Stem Cells

12.3.9 - Local Administration of Magnesium Promotes Meniscal Healing Through Homing of Endogenous Stem Cells: A Proof-of-Concept Study

Presentation Number
12.3.9
Presentation Topic
Stem Cells
Lecture Time
18:12 - 18:21
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Although many strategies have been developed to modify the biological and biomechanical environment of the meniscal suture to improve the chances of healing, the failure rates remain high. Thus, new methods to promote meniscal regeneration and repair are needed. Administration of magnesium (via a repair using magnesium stitches) might enhance recruitment and adherence of
endogenous stem cells to the site of the lesion, thereby promoting in situ meniscal regeneration and chondroprotective functions.

Methods and Materials

Synovial fluid–derived mesenchymal stem cells (SMSCs) were identified and isolated from the knees of rabbits with a meniscal injury of 4 weeks’ duration. An in vitro analysis of adherence and chemotaxis of SMSCs was performed. For the in vivo assay, rabbits (n = 120) with meniscal lesions were divided into 3 groups: repair with high-purity magnesium stitches (Mg group), repair with absorbable sutures (Control group), and no repair (Blank group). Healing of the regenerated tissue and degeneration of the articular cartilage were evaluated by gross and histological analysis at postoperative weeks 1, 3, 6, and 12. The mechanical properties of the repaired meniscus were also analyzed (tensile testing).

Results

In vitro, magnesium promoted the adhesion and migration of SMSCs, which were identified and increased in the knee joints with meniscal lesions. Moreover, fibrochondrogenesis of SMSCs was stimulated by magnesium. Compared with the other groups, the Mg group had enhanced tissue regeneration, lower cartilage degeneration, and retained mechanical strength at 12 weeks after meniscal repair.

Conclusion

Magnesium could be used for in situ meniscal repair due to the potential capacity of magnesium to recruit endogenous stem cells and promote synthesis of fibrocartilaginous matrix. This study suggests the potential of magnesium in recruiting endogenous stem cells for in situ meniscal repair; however, this approach needs to be further investigated before being applied clinically.

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Podium Presentation Allografts

23.2.5 - Elliptical, Stacked, and Single Osteochondral Allograft Transplantation for Large Knee Chondral Defects: One-Year MRI Outcomes

Presentation Number
23.2.5
Presentation Topic
Allografts
Lecture Time
11:06 - 11:15
Session Name
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Osteochondral allograft transplantation (OCA) is a proven cartilage restoration procedure for patients with large chondral defects. However, elongated condylar lesions pose a challenge for dowel OCA in restoring articular surface congruity. Recently, instrumentation to harvest a single, elliptical allograft (BioUni, Arthrex) has been developed for treating ovoid lesions without requiring an adjacent-plug (stacked or snowman) technique (Figure 1). The purpose of this study was to compare 1-year MRI outcomes of patients treated with elliptical, stacked, or single OCA using the Osteochondral Allograft MRI Scoring System (OCAMRISS) and percent osseous integration.

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Methods and Materials

A retrospective review on patients treated from 2000 to 2018 with OCA for condylar defects of the knee was conducted. Inclusion criteria included those followed prospectively with a MRI at ~1 year after surgery. OCAMRISS and osseous integration scores (0-25%; 26-50%; 51-75%; 76%-100%) were graded by a musculoskeletal radiologist blinded to the outcomes. Comparisons of demographics and MRI scores were performed with the ANOVA.

Results

A total of 48 knees (mean age, 35.8 years; 70% male) met the inclusion criteria and were treated with either elliptical (n=19), stacked (n=19), or single (n=19) OCA. Mean time to post-operative MRI was 10.7, 11.1, and 12.4 months, respectively (p=0.17). There were no significant differences in demographics or number of prior ipsilateral knee surgeries among groups. Bone, cartilage, ancillary, and total OCAMRISS scores were not significantly different between groups (Table 1). A trend towards a higher percentage of osseous integration (single>stacked>elliptical) was noted which correlated with less transplanted allograft bone, however, these differences were not significant (p=0.15).

table 1.png

Conclusion

One-year OCAMRISS and osseous integration scores did not differ among patients treated with elliptical, stacked, or single OCA. Further investigation is needed to explore potential differences in clinical outcomes and long-term osseous integration between elliptical and stacked OCA for the treatment of elongated condylar defects of the knee.

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Podium Presentation Microfracture/Bone Marrow Stimulation

12.2.3 - Modulation of Inflamed Synovium and its Residing Macrophages Improves in vitro Migration of Mesenchymal Stromal Cells

Presentation Number
12.2.3
Presentation Topic
Microfracture/Bone Marrow Stimulation
Lecture Time
17:18 - 17:27
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Therapeutic solutions aiming to stimulate endogenous repair of osteochondral defects by using scaffolds or hydrogels are emerging. To achieve good integrative repair, mesenchymal stromal cells from the underlying bone marrow (BMSCs) should migrate into the hydrogel/scaffold and deposit extracellular matrix. Osteochondral defects are often accompanied by synovial inflammation. We investigated how synovial inflammation influences BMSC migration, and whether modulation of inflammation improves migration.

Methods and Materials

Osteoarthritic synovial tissue explants were cultured with/without 1 µM triamcinolone acetonide (TAA) for 24 hours to obtain synovium conditioned medium (SCM). The effect of 6 SCM donors on migration of passage 3 BMSCs was examined in a boyden chamber assay. Inflammation of the synovial explants was assessed with gene expression analysis and flow cytometry of synovial macrophages. Human peripheral blood monocytes were stimulated with TNF-α/IFN-γ towards pro-inflammatory macrophages, with IL-4 towards repair macrophages, and with IL-10 towards anti-inflammatory macrophages and their conditioned medium was used to assess BMSC migration on a collagen gel.

Results

SCM resulted in a donor dependent increase in MSC migration. Modulation of synovial inflammation with TAA significantly decreased expression of TNFA, IL1B and IL6, genes associated with inflammation, and increased gene expression of CD163, associated with anti-inflammatory macrophages, in synovial tissue explants. The percentage of CD14+CD80+(p<0.001) or CD14+CD86+(p<0.001) pro-inflammatory macrophages was lower in TAA-treated samples, whereas the percentage of CD14+CD163+ [KS1] anti-inflammatory macrophages was higher(p<0.001) than without TAA. Modulation of synovial inflammation with TAA resulted in a 1.5-fold increase(p<0.01) in migration. Moreover, BMSC migration in collagen gel increased 2.5-fold(p<0.001) in response to medium conditioned by repair macrophages, and 2.3-fold(p<0.01) by anti-inflammatory macrophages. Migration was unaffected by pro-inflammatory macrophage CM.

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Conclusion

Decreased synovial inflammation increased BMSC migration. Modulation of inflammation, and macrophage phenotype in synovium using TAA seems promising to enhance BMSC migration. This knowledge could be used in approaches stimulating endogenous repair of osteochondral defects.

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Podium Presentation Osteoarthritis

23.2.8 - Anterior tibiotalar fat pad morphology and signal intensity on MRI are correlated with patient characteristics and joint pathology

Presentation Number
23.2.8
Presentation Topic
Osteoarthritis
Lecture Time
11:33 - 11:42
Session Name
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

In this study, we tried to investigate the innovative concept of the ATFP as missing link in the pathogenesis of persistent complaints after ankle sprain and potential source driving inflammation in the development of ankle osteoarthritis.

Methods and Materials

The present study is a secondary analysis of an observational case control study by Van Ochten et al. We included 106 patients with a Kellgren & Lawrence score of 0 in the tibiotalar joint on x-ray. T1 MRI scans were assessed for the signal intensity and area of the ATFP by mapping the fat pad in ‘Mimics 18.0’. After importing those mapped scans in the program ‘MATHLAB’, quantitative values of intensity and area were generated. Those values were statistically tested for correlations with patient characteristics and structural abnormalities by univariate and multivariate linear regression.

Results

MRI signal intensity of the ATFP is associated with BMI (p= 0.03), sex (p<0.01) and age (p= 0.01). ATFP area is correlated with sex (p<0.01) and presence of pre-OA signs in the subtalar joint (p= 0.01). After multivariate analysis, correcting for sex, subtalar pre-OA signs and BMI, persistent complaints were associated with ATFP area (p= 0.04).

Conclusion

This study demonstrates the involvement of the ATFP in hindfoot joint pathology. ATFP MRI characteristics were also influenced by patient characteristics. Further research should confirm these findings in a more elaborate population including OA patients, focus on histological validation and determine underlying pathogenic processes that may explain the observed correlations.

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Podium Presentation Osteoarthritis

16.3.2 - Syndecan-4 is Increased in Osteoarthritic Knee, but not Hip or Shoulder, Articular Hypertrophic Chondrocytes

Presentation Number
16.3.2
Presentation Topic
Osteoarthritis
Lecture Time
11:24 - 11:33
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Syndecans are transmembrane heparan sulfate proteoglycans that regulates cell-matrix interactions. Though their glycosaminoglycan chains, syndecans interact with a variety of extracellular matrix molecules as well as with growth factors and cytokines. They are involved especially in embryonic development, tumorigenesis, and angiogenesis Syndecans are expressed by chondrocytes] but their role in cartilage homeostasis or degradation remain poorly documented. We suspect that syndecan-4 plays a critical role in cartilage degradation during osteoarthritis (OA).The aim of this study was to investigate the expression and localization of syndecan-4 in different OA joint tissues.

Methods and Materials

Syndecan-4 mRNA levels were quantified by RT-PCR in human OA primary cells. Syndecan-4 was localized by immunohistochemistry in knee, hip or shoulder OA bone/cartilage biopsies. Syndecan-4 was quantified by immmunoassay in chondrocytes culture supernatant and cell fraction.

Results

Using immunochemistry, syndecan-4 was observed in chondrocytes clusters in the superficial zone of OA knee, but not in OA hip or shoulder cartilage. No significant difference was detected in syndecan-4 expression level in sclerotic compared to non-sclerotic osteoblasts or in inflamed synoviocytes compared to normal/reactive ones. Differentiated hypertrophic chondrocytes from knee, but not from hip cartilage, expressed more syndecan-4 than non-hypertrophic cells. Using an immunoassay for the extracellular domain of syndecan-4, we found 68% of the syndecan-4 in the culture supernatant of OA chondrocytes culture, suggesting that a large majority of the syndecan-4 is shed and released in the extracellular medium. The shedding rate was not affected by hypertrophic differentiation state of the chondrocytes or their joint origin.

Conclusion

Even if chondrocytes clusters are seen in OA knee, hip and shoulder cartilage and hypertrophic differentiation appears in knee and hip OA articular chondrocytes, syndecan-4 synthesis only increased in knee. These findings suggests the presence of biochemical difference between articular cartilage according to their location and that syndecan-4 could be a biochemical marker specific for knee OA.

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Podium Presentation Cartilage /Cell Transplantation

23.1.9 - Severe bone marrow edema following prior marrow stimulation technique is a predictor of autologous chondrocyte implantation failure.

Presentation Number
23.1.9
Presentation Topic
Cartilage /Cell Transplantation
Lecture Time
11:42 - 11:51
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Autologous chondrocyte implantation (ACI) is a well-established cartilage repair procedure, however, numerous studies have shown higher ACI graft failure rates after prior marrow stimulation techniques (MST). The purpose of this study was to identify which factors may predict decreased graft survival after ACI among patients who underwent prior MST. A secondary aim was to investigate the specificity of these predictors.

Methods and Materials

In this review of prospectively collected data, we analyzed 38 patients who had failed prior MST surgery and subsequently underwent collagen covered ACI (case group). We divided our patient case group to graft failure ACI (n=8, 21%) and successful ACI (n=30, 79%). Fourteen clinical variables were categorized and analyzed to determine predictors for failure of the ACI graft. Preoperative magnetic resonance imaging (MRI) was used to evaluate the severity of subchondral bone marrow edema (BME) graded from I–absent to IV–severe, the presence of subchondral cyst, hypertrophic sclerosis, and intralesional osteophyte. The effects of these MRI findings on the graft survivor were also investigated. Concurrently, a control group, without prior MST was matched to investigate the specificity of the previously determined predictor.

Results

In the case group, the presence of preoperative severe BME was significantly higher in patients with failed ACI as compared to patients with successful ACI (p<0.001). In the control group the presence of severe BME was not significantly different between the failure and successful group (p=0.747). ACI graft failure rate among patients with prior MST and preoperative grade IV BME was 83.7% at 5 years postoperatively resulting a significantly lower survival rate as compared to patients with prior MST and without severe BME (5-year graft failure rate=6.5%) (p < 0.001). Other parameters did not differ significantly.

Conclusion

The presence of grade IV BME after prior MST is a predictive factor for graft failure among patients who then underwent second-generation ACI.

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Podium Presentation Animal Models

23.2.4 - The development of a magnetic resonance scoring system for evaluating osteochondral healing in preclinical models – the 'AMOS’ score.

Presentation Number
23.2.4
Presentation Topic
Animal Models
Lecture Time
10:57 - 11:06
Session Name
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

The purpose of this study was to create and assess the reliability of an Animal Magnetic resonance imaging Osteochondral Score (AMOS) to evaluate the healing of experimentally created osteochondral defects in preclinical models.

Methods and Materials

The AMOS score consists of an objective score and four subjective scores (integration, repair tissue surface, infill signal intensity and signal change outside surgical site). The AMOS score was applied to lesions in forty-six sheep using an ovine medial femoral condyle osteochondral defect model as an exemplar. These defects were subsequently evaluated histologically using the modified O’Driscoll score.

Results

The AMOS scores recorded ranged from 35 to 100. The AMOS score had 92.5% inter-rater reliability and 80% intra-rater reliability for the four subjective components. The mean inter-rater-reliability was 85% (+/- >1%) for integration; for intensity of infill, the mean inter-rater reliability was 95% (+/- 0%); the mean intra-reliability was 92.5% (+/- 2.5%) for repair tissue surface; and the mean inter-rater reliability was 97.5% (+/- 2.5%) for signal change outside the operated site. No correlation was found between the AMOS score and the modified O’Driscoll score.

Conclusion

The AMOS score had high inter-rater reliabilities, suggesting that it would be an effective scoring system. The AMOS score is a user-friendly semi-quantitative method of assessing osteochondral defect from magnetic resonance appearance for following ovine defect changes. The lack of correlation between AMOS and histological scorings reflects their different sensitivities to healing, suggesting that the AMOS score is complementary to histological evaluation.

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Podium Presentation Cartilage and Meniscus

12.3.6 - 3D bioprinted meniscus tissue-like structure using gene edited iPS cell -line and chondrocytes induces the cartilage marker ACAN

Presentation Number
12.3.6
Presentation Topic
Cartilage and Meniscus
Lecture Time
17:45 - 17:54
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Pathological changes of the meniscus are common in people with Osteoartrithis (OA) and damage to the meniscus often leads to secondary OA. Meniscus architecture is individual and a perfect match is suggested to be key for successful transplantation. For this reason and due to the limited availability of donor meniscus other strategies such as 3D bioprinting is sought for.

Methods and Materials

Herein we 3D bioprinted a meniscus prototype including human induced pluripotent stem cells (iPSCs) together with human chondrocytes, using nanocellulose/alginate containing bioink previously published. Chondrocytes were obtained from autologous chondrocyte implantation (ACI) surgery and the iPSC line was generated by reprogramming the chondrocytes. CRISPER-Cas9 gene editing of the chondrocyte derived iPSC line was used to insert the green fluorescence protein (GFP) under control of the aggrecan promoter (ACAN). After printing the meniscus prototypes were placed in chondrogenic-differentiation medium for 3 weeks. Sections of the 3D bioprinted meniscus were stained by Alcian Blue van Gieson stainining. The aggrecan expression (ACAN) analysis of the 3D bioprinted iPSC/Chondrocytes was performed after 3 weeks using fluorescence imaging microscope IN Cell Analyzer 6000 (IN Cell 6000, GE Healthcare, United Kingdom).

Results

Meniscus-like tissue structures were reproducible obtained and could be scaled down and printed in 96 well format (Figure). Proteoglycan staining supported differentiation along the fibrous-cartilage lineage similar to what is normally seen in meniscus native tissue. The cartilage marker ACAN was induced in the GFP positive cells so that they can be traced back to the gene edited iPSCs and darker areas were assumed to originate from the human chondrocytes. Vascular-like tubes could be seen in sections and the surrounding endothelial cells were developed from the iPSC population based on visualization of GFP expression.

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Conclusion

In this study we were able to produce a meniscus structure by 3D bioprinting multiple meniscus prototypes resembling native meniscus tissue.

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Podium Presentation Intervertebral Disc

18.3.6 - Therapeutic effects of gefitinib-encapsulated thermosensitive injectable hydrogel in intervertebral disc degeneration

Presentation Number
18.3.6
Presentation Topic
Intervertebral Disc
Lecture Time
15:00 - 15:09
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Intervertebral disc (IVD) degeneration is one of the most widespread musculoskeletal diseases world- wide, which remains an intractable clinical challenge. The aim of this study is to investigate the thera- peutic potential of the small molecule gefitinib (an epidermal growth factor receptor (EGFR) inhibitor) in ameliorating IVD degeneration.

Methods and Materials

MRI and histological staining were performed to confirm degeneration of the rat and human IVDs. To investigate the functions of EGFR in IVD pathogenesis, we created an inducible Egfr deletion system using Col2a1-CreERT2; Egfrf/f mice. We next evaluated the effect of pharmacological inhibition of EGFR signaling with gefitinib on IVD degeneration. Puncture-induced rat IVD degeneration model was established to evaluate the therapeutic effect of gefitinib-encapsulated ther- mosensitive injectable hydrogel in vivo.

Results

Aberrant EGFR activation levels were detected in both human and rat degenerative IVDs, which prompted us to investigate the functional roles of EGFR by utilizing inducible cartilage-specific EGFR-deficient mice. We demonstrated that conditional EGFR deletion in mice increased nucleus pulposus (NP) extracellular matrix (ECM) production and autophagy marker activation while MMP13 expression decreased. These outcomes are comparable to the use of a controlled-release injectable thermosensitive hydrogel of gefitinib to block EGFR activity in a puncture-induced rat model. We also conducted a case series study involving patients with non-small cell lung cancer and IVD degeneration who received gefitinib treatment from 2010 to 2015. Gefitinib-treated patients displayed a relative slower disc degenerating progression, in contrast to control subjects.

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Conclusion

These findings thus provide evidence that suppression of EGFR by the FDA-approved drug gefitinib can protect IVD degeneration in rats, implying the potential application of gefitinib as a small molecule drug for treating IVD degeneration.

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Podium Presentation Osteoarthritis

12.2.4 - Transcriptional profiling of murine macrophages stimulated with cartilage fragments reveals a novel mechanism for osteoarthritis

Presentation Number
12.2.4
Presentation Topic
Osteoarthritis
Lecture Time
17:27 - 17:36
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Osteoarthritis (OA) is a progressive joint disease characterized by loss of articular cartilage and synovial inflammation accompanied by pain and disability. Synovial macrophages avidly engulf cartilage fragments and release inflammatory cytokines that exaggerates the osteoarthritic process and severity of disease. However, molecular mechanisms by which cartilage fragments triggers cellular responses are unclear and remain to be investigated. Therefore, the current study aims at analyzing molecular response of macrophages to cartilage fragments as step towards identifying molecular candidates for potential therapies.

Methods and Materials

Bone marrow derived macrophages and femoral head cartilages were isolated from C57/B6 mice. Cartilage fragments were prepared using optimal procedure for obtaining fragments similar to these isolated from synovial fluid of OA patients. Macrophages were co-cultured with cartilage fragments for 24h, and then harvested for RNA extraction and RNA sequencing. Data were analyzed for sequence alignment, transcript quantification, mapping and annotating. Significantly expressed genes with p-value ≤ 0.01 were subjected to gene ontology and pathway enrichment analyses.

Results

A total 153 genes were differentially upregulated, and 110 genes were down-regulated in response to cartilage fragments (Fig. 1). GO enrichment analysis revealed that the upregulated genes were mainly categorized into 11, 7, and 11 GO terms for cellular components, molecular function and biological process (p ≤ 0.001), respectively. The most significantly enriched terms included extracellular exosome, scavenger receptor activity, and innate immune response. (Fig. 2) Upregulated genes in response to cartilage fragments were enriched in 8 KEGG pathways including TNF-a signaling pathway, and toll-like receptor signaling. Moreover, ATF2, STAT3, ESR1, and NFKB1 were the most significantly enriched transcriptional factors in this response.2019 icrs f1.jpg2019 icrs f2.jpg

Conclusion

Bioinformatic analysis revealed that stimulated macrophages elicited common gene expression signature for inflammation, including activation of toll-like receptors, and TNF-α and NFKB signaling. Such data broaden our knowledge of the immunological response of macrophages to cartilage fragments and their role in osteoarthritic process.

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Podium Presentation Chondrocytes

16.2.3 - Volume-by-volume bioprinting of chondrocytes-alginate bioinks in high temperature thermoplastic scaffolds for cartilage regeneration

Presentation Number
16.2.3
Presentation Topic
Chondrocytes
Lecture Time
11:33 - 11:42
Session Name
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

The objective of this study was to develop a novel volume-by-volume 3D-biofabrication process that divides the printed part into different volumes and injects the cells after each volume has been printed, once the temperature of the printed thermoplastic fibers has decreased. This novel 3D-biofabrication procedure prints a mesh structure layer-by-layer with a high adhesion surface/volume ratio, driving a rapid decrease in the temperature, avoiding contact with cells in high temperature zones. In our study, chondrocytes survived the manufacturing process and after seven days in culture, chondrocytes proliferated and totally colonized the scaffold.

Methods and Materials

A bioprinter with three syringes and one FDM extruder consisting of hardware, designer software with the algorithms that allow the configuration of VbV, and an electronic control unit (ECU) that connects the software to the hardware, were used for the experiments

Results

Results showed an incremental growth in the number of cells, with a stabilization of growth between day 5 and day 7. After 24 h in culture, individual cells with rounded shape appeared; however, seven days later, chondrocytes were able to migrate and proliferate throughout the scaffolds, completely colonizing the PLA fibers, and forming a homogeneous surface. Cell density, was calculated over volume of the scaffold. At seven days, positive cells were found per 1 mm3 of scaffold, being a total of 1,423,000 of cells per 1000 mm3 (total volume of the scaffold).

Conclusion

In conclusion, we have shown that a novel VbV-based bioprinting method enhances chondrocyte survival and distribution within the bioprinted scaffolds, using high temperature thermoplastic without scaffold mesh geometry limitations. VbV solves the two main complications of common bioprinting techniques: 1. it can be used with already clinically approved biomaterials and, 2. this process does not have restrictions in geometries that could limit the clinical application of 3D bioprinting in cartilage TE.

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Podium Presentation Stem Cells

18.2.2 - Progenitors from Cartilage, Bone Marrow, Infrapatellar fat pad, Synovium, Periosteum – A Quantitative Comparison for Cartilage Repair

Presentation Number
18.2.2
Presentation Topic
Stem Cells
Lecture Time
14:24 - 14:33
Session Type
Free Paper Session
Corresponding Author
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

Cell-based therapy for cartilage repair is becoming an established technique for modern healthcare. Unfortunately, there is no consensus on an optimal cell source yet. The study provides a donor-matched quantitative comparison of the connective tissue progenitors (CTPs) derived from cartilage (Outerbridge grade G1-2-3), bone marrow aspirate concentrate (BMC), infrapatellar fat pad (IPFP), synovium (SYN) and periosteum (PERI) with respect to: 1) cell concentration (cells/cc), 2) CTP prevalence (colony forming units per million cells), and 3) biological performance based on in vitro proliferation (cells per colony), migration (colony density) and differentiation (expression of negatively charged extracellular matrix: GAG-ECM) potentials.

Methods and Materials

Ten patients undergoing total knee arthroplasty (mean-age: 59years, females=6) were recruited. Automated ASTM-based quantitative colony forming unit assay was used to compare cell concentration, CTP prevalence, and biological performance across tissue sources. A significance level of 0.05 was used overall. Tukey’s multiple comparison method was used to exam all pairwise comparisons between cell sources.

Results

Cell concentration was highest in G3 (p=0.002) and BMC (p=0.001). CTP prevalence was highest in IPFP (p=0.001), SYN (p=0.003) and G1-2 cartilage (p=0.02). Proliferation potential was highest in SYN (p<0.001) derived CTPs. Migration potential was highest in G1-2-3 (p<0.001). Differentiation potential was highest in G1-2-3 (p<0.001). CTPs derived from any given tissue sources and any given individual were highly heterogeneous in biological performance.

Conclusion

Data presented in this study suggests that cartilage (G1-2-3) is the preferred tissue source for cartilage repair, based on PCTP and GAG-ECM, followed by SYN, IPFP, BMC and PERI. However, within each tissue source, there exists a subset of CTPs with biological performance similar to G1-2-3 cartilage, particularly in SYN and IPFP. Refinements to current cell expansion strategies, particularly performance-based clonal selection and expansion of preferred CTPs and their progeny can potentially lead to improved cell population with predictive future.

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