Granulocyte macrophage - colony stimulating factor (GM-CSF) significantly enhances articular cartilage repair potential by microfracture

Enhancers of mesenchymal stem cell stemness and therapeutic potency

Mesenchymal stem cells (MSCs) are multipotent stromal cells that can differentiate into a range of cell types, including osteoblasts, chondrocytes, myocytes, and adipocytes. Multiple preclinical investigations and clinical trials employed enhanced MSCs-dependent therapies in treatment of inflammatory and degenerative diseases. They have demonstrated considerable and prospective therapeutic potentials even though the large-scale use remains a problem. Several strategies have been used to improve the therapeutic potency of MSCs in cellular therapy. Treatment of MSCs utilizing pharmaceutical compounds, cytokines, growth factors, hormones, and vitamins have shown potential outcomes in boosting MSCs' stemness. In this study, we reviewed the current advances in enhancing techniques that attempt to promote MSCs' therapeutic effectiveness in cellular therapy and stemness in vivo with potential mechanisms and applications.

O2 variant chip to simulate site-specific skeletogenesis from hypoxic bone marrow

The stemness of bone marrow mesenchymal stem cells (BMSCs) is maintained by hypoxia. The oxygen level increases from vessel-free cartilage to hypoxic bone marrow and, furthermore, to vascularized bone, which might direct the chondrogenesis to osteogenesis and regenerate the skeletal system. Hence, oxygen was diffused from relatively low to high levels throughout a three-dimensional chip. When we cultured BMSCs in the chip and implanted them into the rabbit defect models of low-oxygen cartilage and high-oxygen calvaria bone, (i) the low oxygen level (base) promoted stemness and chondrogenesis of BMSCs with robust antioxidative potential; (ii) the middle level (two times ≥ low) pushed BMSCs to quiescence; and (iii) the high level (four times ≥ low) promoted osteogenesis by disturbing the redox balance and stemness. Last, endochondral or intramembranous osteogenesis upon transition from low to high oxygen in vivo suggests a developmental mechanism-driven solution to promote chondrogenesis to osteogenesis in the skeletal system by regulating the oxygen environment.

Microfracture Augmentation With Direct In Situ Radial Shockwave Stimulation With Appropriate Energy Has Comparable Repair Performance With Tissue Engineering in the Porcine Osteochondral Defect Model

BACKGROUND

The first-line clinical strategy for small cartilage/osteochondral defects is microfracture (MF). However, its repair efficacy needs improvement.

HYPOTHESIS

Appropriate energy radial shockwave stimulation in MF holes would greatly improve repair efficacy in the porcine osteochondral defect model, and it may obtain comparable performance with common tissue engineering techniques.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteochondral defect models (8-mm diameter, 3-mm depth) were established in the weightbearing area of Bama pigs' medial femoral condyles. In total, 25 minipigs were randomly divided into 5 groups: control (Con; without treatment), MF, MF augmentation (MF+; treated with appropriate energy radial shockwave stimulation in MF holes after MF), tissue engineering (TE; treated with compounds of microcarrier and bone marrow mesenchymal stem cells), and sham (as the positive control). After 3 months of intervention, osteochondral specimens were harvested for macroscopic, radiological, biomechanical, and histological evaluations. The statistical data were analyzed using 1-way analysis of variance.

RESULTS

Based on the macroscopic appearance, the smoothness and integration of the repaired tissue in the MF+ group were improved when compared with the Con and MF groups. The histological staining suggested more abundant cartilaginous matrix deposition in the MF+ group versus the Con and MF groups. The general scores of the macroscopic and histological appearances were comparable in the MF+ and the TE groups. The high signal areas of the osteochondral unit in the magnetic resonance images were significantly decreased in the MF+ group, with no difference with the TE group. The micro-computed tomography data demonstrated the safety of direct in situ radial shockwave performance. Biomechanical tests revealed that the repaired tissue's Young modulus was highest in the MF+ group and not statistically different from that in the TE group.

CONCLUSION

Direct in situ radial shockwave stimulation with appropriate energy significantly improves the short-term repair efficacy of MF. More encouragingly, the MF+ group in our study obtained repair performance comparable with the TE therapy.

CLINICAL RELEVANCE

This strategy is easy to perform and can readily be generalized with safety and higher cartilage repair efficacy. Moreover, it is expected to be accomplished under arthroscopy, indicating tremendous clinical transformative value.

Effect of Systemic Administration of Granulocyte Colony-Stimulating Factor on a Chronic Partial-Thickness Cartilage Defect in a Rabbit Knee Joint

OBJECTIVE

Cartilage lesions in the knee joint can lead to joint mechanics changes and cause knee pain. Bone marrow stimulation (BMS) promotes cartilage regeneration by perforating the subchondral bone just below the injury and inducing bone marrow cells. This study aimed to investigate whether systemic administration of granulocyte colony-stimulating factor (G-CSF) with BMS improves repair of chronic partial-thickness cartilage defects (PTCDs).

DESIGN

Eighteen 6-month-old New Zealand white rabbits were divided into 3 groups: control (C, n = 6), BMS alone (n = 6), and BMS + G-CSF (n = 6). Partial cartilage defects with 5 mm diameter were created in the trochlear region of both knees; after 4 weeks, the BMS alone and BMS + G-CSF groups underwent BMS; G-CSF (50 µg/kg) or saline was administered subcutaneously for 5 days starting from 3 days before BMS. At 8 and 16 weeks after cartilage defect creation, the area of cartilage defects was macroscopically and histologically evaluated.

RESULTS

International Cartilage Repair Society (ICRS) grades for macroscopic assessment were 0, 0.7, and 0.7 at 8 weeks and 0, 1.2, and 1.3 at 16 weeks in the C, BMS, and BMS + G-CSF groups, respectively. Wakitani scores for histological assessment were 9.8, 8.7, and 8.2 at 8 weeks and 9.5, 9, and 8.2 at 16 weeks in the C, BMS, and BMS + G-CSF groups, respectively. The BMS + G-CSF group showed significantly more repair than the C group, but there was no difference from the BMS group.

CONCLUSIONS

The effect of BMS and G-CSF on chronic PTCDs in mature rabbit knees was limited.

Human ESC-derived Neuromesodermal Progenitors (NMPs) Successfully Differentiate into Mesenchymal Stem Cells (MSCs)

Mesenchymal Stem Cells (MSCs), as an adult stem cell type, are used to treat various disorders in clinics. However, derivation of homogenous and adequate amount of MSCs limits the regenerative treatment potential. Although mesoderm is the main source of mesenchymal progenitors during embryonic development, neuromesodermal progenitors (NMPs), reside in the primitive streak during development, is known to differentiate into paraxial mesoderm. In the current study, we generated NMPs from human embryonic stem cells (hESC), subsequently derived MSCs and characterized this cell population in vitro and in vivo. Using a bFGF and CHIR induced NMP formation protocol followed by serum containing culture conditions; here we show that MSCs can be generated from NMPs identified by not only the expression of T/Bra and Sox 2 but also FLK-1/PDGFRα in our study. NMP-derived MSCs were plastic adherent fibroblast like cells with colony forming capacity and trilineage (osteo-, chondro- and adipo-genic) differentiation potential. In the present study, we demonstrate that NMP-derived MSCs have an endothelial tendency which might be related to their FLK-1+/PDGFRα + NMP origin. NMP-derived MSCs displayed a protein expression profile of characterized MSCs. Growth factor and angiogenesis related pathway proteins were similarly expressed in NMP-derived MSCs and characterized MSCs. NMP-derived MSCs keep characteristics after short-term and long-term freeze-thaw cycles and localized into bone marrow followed by tail vein injection into NOD/SCID mice. Together, these data showed that hESC-derived NMPs might be used as a precursor cell population for MSC derivation and could be used for in vitro and in vivo research.

Motorized Shaver Harvest Results in Similar Cell Yield and Characteristics Compared With Rongeur Biopsy During Arthroscopic Synovium-Derived Mesenchymal Stem Cell Harvest

PURPOSE

To compare cell yield and character of synovium-derived mesenchymal stem cell (SDMSC) harvested by 2 different techniques using rongeur and motorized shaver during knee arthroscopy.

METHODS

This study was performed in 15 patients undergoing partial meniscectomy. Two different techniques were used to harvest SDMSCs in each patient from the synovial membrane at 2 different locations overlying the anterior fat pad, each within 1 minute of harvest time. Cell yield and proliferation rates were evaluated. Cell surface marker analysis was done after passage 2 (P2). Trilineage differentiation potential was evaluated by real-time quantitative polymerase chain reaction and histology. Statistical analysis between the 2 methods was done using the Mann-Whitney U test.

RESULTS

Wet weight of total harvested tissue was 69.93 (± 20.02) mg versus 378.91 (± 168.87) mg for the rongeur and shaver group, respectively (P < .0001). Mononucleated cell yield was 3.32 (± 0.89) versus 3.18 (± 0.97) × 10³ cells/mg, respectively (P = .67). Fluorescence-activated cell sorting analysis revealed similar SDMSC-related cell surface marker expression levels in both groups, with positive expression for CD44, CD73, CD90, and CD105 and decreased expression for CD34 and CD45. Both groups showed similar trilineage differentiation potential in histology. Chondrogenic (SOX9, ACAN, COL2), adipogenic (LPL, PLIN1, PPAR-γ), and osteogenic (OCN, OSX, RUNX2) gene marker expression levels also were similar between both groups.

CONCLUSIONS

No difference was observed between rongeur biopsy and motorized shaver harvest methods regarding SDMSC yield and cell characteristics.

CLINICAL RELEVANCE

The current study shows that both rongeur and motorized shaver harvest are safe and effective methods for obtaining SDMSCs. Motorized shaver harvest results in higher volume of tissue acquisition per time, thereby leading to higher number of SDMSCs which may be useful during clinical application.

Using apheresis-derived cells to augment microdrilling in the treatment of chondral defects in an ovine model

The treatment of chondral defects using microdrilling often results in a mechanically weak fibrocartilagenous repair, rather than a more robust hyaline cartilage repair. Many different microfracture/microdrilling augmentation techniques have been described, including the use of cellular products to enhance healing. Autologous peripheral blood progenitor cells can be obtained via apheresis after administration of granulocyte colony-stimulating factor (G-CSF) and have been used successfully to augment microdrilling in clinical patients. The objective of this study was to use apheresis-derived mononuclear blood cells to augment microdrilling treatment of a cartilage defect in an ovine model to determine the effect on healing. Forty adult female sheep were used in this study and were divided into a control group (microdrilling alone) and a treatment group (microdrilling, hyaluronic acid, and apheretic product). Outcome measurements included weight-bearing on the operated limb, macroscopic scoring of the joint, histology, and immunohistochemistry. In addition, magnetic resonance imaging was used to attempt to identify SPION-labeled cells from the apheretic product in the operated limbs. The results showed a significant increase in healing as measured by the modified O'Driscoll sore in the treated group. No evidence of homing of SPION-labeled cells to the defect was found and no correlation was found between the response to G-CSF administration or concentration of CD34⁺  and outcome. A correlation was found between healing and the concentration of white blood cells and peripheral blood mononuclear cell numbers in the apheretic product.

Cellular Response to Individual Components of the Platelet Concentrate

Platelet concentrates and especially their further product platelet lysate, are widely used as a replacement for cell culturing. Platelets contain a broad spectrum of growth factors and bioactive molecules that affect cellular fate. However, the cellular response to individual components of the human platelet concentrate is still unclear. The aim of this study was to observe cellular behavior according to the individual components of platelet concentrates. The bioactive molecule content was determined. The cells were supplemented with a medium containing 8% (v/v) of platelet proteins in plasma, pure platelet proteins in deionized water, and pure plasma. The results showed a higher concentration of fibrinogen, albumin, insulin growth factor I (IGF-1), keratinocyte growth factor (KGF), and hepatocyte growth factor (HGF), in the groups containing plasma. On the other hand, chemokine RANTES and platelet-derived growth factor bb (PDGF-bb), were higher in the groups containing platelet proteins. The groups containing both plasma and plasma proteins showed the most pronounced proliferation and viability of mesenchymal stem cells and fibroblasts. The platelet proteins alone were not sufficient to provide optimal cell growth and viability. A synergic effect of platelet proteins and plasma was observed. The data indicated the importance of plasma in platelet lysate for cell growth.

A Simple Method to Reduce the Incidence of Cyclops Lesion after Anterior Cruciate Ligament Reconstruction

The purpose of this study is to determine the influence of debridement in and around the bone tunnels on the prevalence of cyclops lesion (CL), after anterior cruciate ligament reconstruction (ACLR) with hamstring grafts. Our hypothesis was that bone tunnel debridement during ACLR would reduce the prevalence of CL. Methods for debridement in and around the bone tunnels after tunnel drilling were standardized and applied to 38 knees undergoing double-bundle ACLR between 2011 and 2014, Group A (debridement group). Group B (nondebridement group) included 56 knees in which bone tunnel debridement was not performed. Postoperative MRI was performed to evaluate the presence of CL and the following three criteria: (1) the intercondylar site of CL (grade 1-3), depending on its anterior extent along the femoral condyle; (2) posterior bowing of the ACL graft; and (3) the positional relationship between the frontmost fiber of ACL graft and Blumensaat's line. If CL caused loss of extension or pain or discomfort during knee extension, it was defined as symptomatic CL (SCL). CL was detected in 8 cases (21.1%) in Group A and 26 cases (46.4%) in Group B. The prevalence of CL was significantly lower in Group A than in Group B (p = 0.010), and the risk ratio of CL was 0.31 (95% confidence interval: 0.12-0.79). Furthermore, 10 patients in Group B had SCL, compared with none in Group A (p = 0.004). In Group A, the intercondylar site of CL was grade 1 in all cases, while in Group B, the CL grades were 1 (n = 17), 2 (n = 7), 3 (n = 2) (p = 0.008). There were no cases of posterior bowing of the ACL in Group A, but six cases in Group B (p = 0.023). Debridement in and around the bone tunnel is a simple and effective method of preventing CL and SCL after ACLR. The level of evidence for the study is 3.

A Novel Strategy to Enhance Microfracture Treatment With Stromal Cell-Derived Factor-1 in a Rat Model

Background

Microfracture is one of the most widely used techniques for the repair of articular cartilage. However, microfracture often results in filling of the chondral defect with fibrocartilage, which exhibits poor durability and sub-optimal mechanical properties. Stromal cell-derived factor-1 (SDF-1) is a potent chemoattractant for mesenchymal stem cells (MSCs) and is expressed at high levels in bone marrow adjacent to developing cartilage during endochondral bone formation. Integrating SDF-1 into an implantable collagen scaffold may provide a chondro-conductive and chondro-inductive milieu via chemotaxis of MSCs and promotion of chondrogenic differentiation, facilitating more robust hyaline cartilage formation following microfracture.

Objective

This work aimed to confirm the chemoattractive properties of SDF-1 in vitro and develop a one-step method for incorporating SDF-1 in vivo to enhance cartilage repair using a rat osteochondral defect model.

Methods

Bone marrow-derived MSCs (BMSCs) were harvested from the femurs of Sprague–Dawley rats and cultured in low-glucose Dulbecco’s modified Eagle’s medium containing 10% fetal bovine serum, with the medium changed every 3 days. Passage 1 MSCs were analyzed by flow cytometry with an S3 Cell Sorter (Bio-Rad). In vitro cell migration assays were performed on MSCs by labeling cells with carboxyfluorescein diacetate, succinimidyl ester (CFDA-SE; Bio-Rad). For the microfracture model, a 1.6-mm-diameter osteochondral defect was created in the femoral trochleae of 20 Sprague–Dawley rats bilaterally until bone marrow spillage was seen under saline irrigation. One knee was chosen at random to receive implantation of the scaffold, and the contralateral knee was left unfilled as an empty control. Type I collagen scaffolds (Kensey Nash) were coated with either gelatin only or gelatin and SDF-1 using a dip coating process. The rats received implantation of either a gelatin-only scaffold (N = 10) or gelatin-and-SDF-1 scaffold (N = 10) at the site of the microfracture. Femurs were collected for histological analyses at 4- and 8-week time points post-operatively, and sections were stained with Safranin O/Fast Green. The samples were graded blindly by two observers using the Modified O’Driscoll score, a validated scoring system for chondral repair. A minimum of 10 separate grading scores were made per sample and averaged. Quantitative comparisons of cell migration in vitro were performed with one-way ANOVA. Cartilage repair in vivo was also compared among groups with one-way ANOVA, and the results were presented as mean ± standard deviation, with P-values < 0.05 considered as statistically significant.

Results

MSC migration showed a dose–response relationship with SDF-1, with an optimal dosage for chemotaxis between 10 and 100 ng/ml. After scaffold implantation, the SDF-1-treated group demonstrated complete filling of the cartilage defect with mature cartilage tissue, exhibiting strong proteoglycan content, smooth borders, and good incorporation into marginal cartilage. Modified O’Driscoll scores after 8 weeks showed a significant improvement of cartilage repair in the SDF-1 group relative to the empty control group (P < 0.01), with a trend toward improvement when compared with the gelatin-only-scaffold group (P < 0.1). No significant differences in scores were found between the empty defect group and gelatin-only group.

Conclusion

In this study, we demonstrated a simple method for improving the quality of cartilage defect repair in a rat model of microfracture. We confirmed the chemotactic properties of SDF-1 on rat MSCs and found an optimized dosage range for chemotaxis between 10 and 100 ng/ml. Furthermore, we demonstrated a strategy to incorporate SDF-1 into gelatin–collagen I scaffolds in vivo at the site of an osteochondral defect. SDF-1-treated defects displayed robust hyaline cartilage resurfacing of the defect with minimal fibrous tissue, in contrast to the empty control group. The results of the in vitro and in vivo studies together suggest that SDF-1-mediated signaling may significantly improve the quality of cartilage regeneration in an osteochondral defect.

HA-g-CS Implant and Moderate-intensity Exercise Stimulate Subchondral Bone Remodeling and Promote Repair of Osteochondral Defects in Mice

Background: Substantial evidence shows that crosstalk between cartilage and subchondral bone may play an important role in cartilage repair. Animal models have shown that hydroxyapatite-grafted-chitosan implant (HA-g-CS) and moderate-intensity exercise promote regeneration of osteochondral defects. However, no in vivo studies have demonstrated that these two factors may have a synergistic activity to facilitate subchondral bone remodeling in mice, thus supporting bone-cartilage repair. Questions: This study was to clarify whether HA-g-CS and moderate-intensity exercise might have a synergistic effect on facilitating (1) regeneration of osteochondral defects and (2) subchondral bone remodeling in a mouse model of osteochondral defects. Methods: Mouse models of osteochondral defects were created and divided into four groups. BC Group was subjected to no treatment, HC Group to HA-g-CS implantation into osteochondral defects, ME group to moderate-intensity treadmill running exercise, and HC+ME group to both HA-g-CS implantation and moderate-intensity exercise until sacrifice. Extent of subchondral bone remodeling at the injury site and subsequent cartilage repair were assessed at 4 weeks after surgery. Results: Compared with BC group, HC, ME and HC+ME groups showed more cartilage repair and thicker articular cartilage layers and HC+ME group acquired the best results. The extent of cartilage repair was correlated positively to bone formation activity at the injured site as verified by microCT and correlation analysis. Histology and immunofluorescence staining confirmed that bone remodeling activity was increased in HC and ME groups, and especially in HC+ME group. This bone formation process was accompanied by an increase in osteogenesis and chondrogenesis factors at the injury site which promoted cartilage repair. Conclusions: In a mouse model of osteochondral repair, HA-g-CS implant and moderate-intensity exercise may have a synergistic effect on improving osteochondral repair potentially through promotion of subchondral bone remodeling and generation of osteogenesis and chondrogenesis factors. Clinical Relevance: Combination of HA-g-CS implantation and moderate-intensity exercise may be considered potentially in clinic to promote osteochondral defect repair. Also, cartilage and subchondral bone forms a functional unit in an articular joint and subchondral bone may regulate cartilage repair by secreting growth factors in its remodeling process. However, a deeper insight into the exact role of HA-g-CS implantation and moderate-intensity exercise in promoting osteochondral repair in other animal models should be explored before they can be applied in clinic in the future.

The effect of distance between holes on the structural stability of subchondral bone in microfracture surgery: a finite element model study

Background

Microfracture is a surgical technique that involves creating multiple holes of 3–4 mm depth in the subchondral bone to recruit stem cells in the bone marrow to the lesion, inducing fibrocartilage repair and knee cartilage regeneration. Recently, it has been reported that increasing the exposed area of the lower cartilaginous bone (drilling a lot of holes) increases the outflow of stem cells, which is expected to affect the physical properties of the subchondral bone when the exposed area is large. The purpose of this study was to analyse the effect of the distance between the holes in the microfracture procedure on the structural stability of the osteochondral bone using a finite element method.

Methods

In this study, lateral aspects of the femoral knee, which were removed during total knee arthroplasty were photographed using microtomography. The model was implemented using a solitary walks program, which is a three-dimensional simplified geometric representation based on the basic microtomography data. A microfracture model was created by drilling 4 mm-deep holes at 1, 1.5, 2, 2.5, 3, 4, and 5 mm intervals in a simplified three-dimensional (3D) geometric femoral model. The structural stability of these models was analysed with the ABAQUS program. We compared the finite element model (FEM) based on the microtomography image and the simplified geometric finite element model.

Results

Von Mises stress of the subchondral bone plate barely increased, even when the distance between holes was set to 1 mm. Altering the distance between the holes had little impact on the structural stability of the subchondral bone plate. Safety factors were all below 1.

Conclusions

Although we did not confirm an optimal distance between holes, this study does provide reference data and an epidemiological basis for determining the optimal distance between the holes used in the microfracture procedure.

Recruiting the innate immune system with GM-CSF to fight viral diseases, including West Nile Virus encephalitis and COVID-19

As the coronavirus disease 2019 (COVID-19) pandemic grows throughout the world, it is imperative that all approaches to ameliorating its effects be investigated, including repurposing drugs that show promise in other diseases. We have been investigating an approach to multiple disorders that involves recruiting the innate immune system to aid the body's healing and regenerative mechanism(s). In the case of West Nile Virus encephalitis and potentially COVID-19, the proposed intervention to stimulate the innate immune system may give the adaptive immune response the necessary time to develop, finish clearing the virus, and provide future immunity. Furthermore, we have found that GM-CSF-induced recruitment of the innate immune system is also able to reverse brain pathology, neuroinflammation and cognitive deficits in mouse models of Alzheimer's disease and Down syndrome, as well as improving cognition in normal aging and in human patients with cognitive deficits due to chemotherapy, both of which exhibit neuroinflammation. Others have shown that GM-CSF is an effective treatment for both bacterial and viral pneumonias, and their associated inflammation, in animals and that it has successfully treated pneumonia-associated Acute Respiratory Distress Syndrome in humans. These and other data strongly suggest that GM-CSF may be an effective treatment for many viral infections, including COVID-19.

Deciphering the Association of Cytokines, Chemokines, and Growth Factors in Chondrogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells Using an ex vivo Osteochondral Culture System

Osteoarthritis (OA) is a chronic degenerative joint disorder associated with degradation and decreased production of the extracellular matrix, eventually leading to cartilage destruction. Limited chondrocyte turnover, structural damage, and prevailing inflammatory milieu prevent efficient cartilage repair and restoration of joint function. In the present study, we evaluated the role of secreted cytokines, chemokines, and growth factors present in the culture supernatant obtained from an ex vivo osteochondral model of cartilage differentiation using cartilage pellets (CP), bone marrow stem cells (BM-MSCs), and/or BM-MSCs + CP. Multiplex cytokine analysis showed differential secretion of growth factors (G-CSF, GM-CSF, HGF, EGF, VEGF); chemokines (MCP-1, MIP1α, MIP1β, RANTES, Eotaxin, IP-10), pro-inflammatory cytokines (IL-1β, IL-2, IL-5, IL-6, IL-8, TNFα, IL-12, IL-15, IL-17) and anti-inflammatory cytokines (IL-4, IL-10, and IL-13) in the experimental groups compared to the control. In silico analyses of the role of stem cells and CP in relation to the expression of various molecules, canonical pathways and hierarchical cluster patterns were deduced using the Ingenuity Pathway Analysis (IPA) software (Qiagen, United States). The interactions of the cytokines, chemokines, and growth factors that are involved in the cartilage differentiation showed that stem cells, when used together with CP, bring about a favorable cell signaling that supports cartilage differentiation and additionally helps to attenuate inflammatory cytokines and further downstream disease-associated pro-inflammatory pathways. Hence, the autologous or allogeneic stem cells and local cartilage tissues may be used for efficient cartilage differentiation and the management of OA.

The pilot-scale preparation of the SA-hGM-CSF bi-functional fusion protein

The granulocyte-macrophage colony-stimulating factor (GM-CSF) can be used to induce a powerful immune response. Based on the specific binding of biotin and streptavidin, SA-hGM-CSF was anchored on the surface of biotinylated tumor cells, which could enhance the anti-tumor effect of tumor cell vaccines in our previous reports, suggesting it would have potential clinical value. Preparation of the biologically active proteins in large-scale production is the basis of clinical application, however, only a small amount of biologically active protein was obtained according to previous studies. In this study, we researched the effects of various factors on the purification and simultaneous renaturation of SA-hGM-CSF fusion protein by single factor experiment and orthogonal experiment. Here, we developed a viable pilot-scale trial in the fermentation, purification, refolding and freeze-drying of SA-hGM-CSF proteins in order to efficiently obtain more biologically active proteins with high purity, which will lay the foundation for industrial production.

The Secretome Derived From 3D-Cultured Umbilical Cord Tissue MSCs Counteracts Manifestations Typifying Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disorder whose treatment is mostly restricted to pain and symptom management and to the delay of joint destruction. Mesenchymal stem/stromal cells from the umbilical cord tissue (UC-MSCs) have previously been proven to be immunomodulatory and more efficient than bone marrow-derived MSCs in causing remission of local and systemic arthritic manifestations in vivo. Given the paracrine nature of UC-MSC activity, their application as active substances can be replaced by their secretome, thus avoiding allogeneic rejection and safety issues related to unwanted grafting. In this work, we aimed at demonstrating the viability of applying the 3D-primed UC-MSC secretome for the amelioration of arthritic signs. A proteomic analysis was performed to both, media conditioned by UC-MSC monolayer (CM2D) and 3D cultures (CM3D). The analysis of relevant trophic factors confirmed secretome profiles with very significant differences in terms of therapeutic potential. Whereas, CM3D was characterised by a prevailing expression of anti-inflammatory cytokines such as IL-10 and LIF, along with trophic factors involved in different mechanisms leading to tissue regeneration, such as PDGF-BB, FGF-2, I-309, SCF, and GM-CSF; CM2D presented relatively higher levels of IL-6, MCP-1, and IL-21, with recognised pro-inflammatory roles in joint disease and pleiotropic effects in the progression of rheumatoid arthritis (RA). Accordingly, different motogenic effects over mouse chondrocytes and distinct capacities of inducing glycosaminoglycan synthesis in vitro were observed between CM3D and CM2D. Finally, the evaluation of arthritic manifestations in vivo, using an adjuvant-induced model for arthritis (AIA), suggested a significantly higher therapeutic potential of CM3D over CM2D and even UC-MSCs. Histological analysis confirmed a faster remission of local and systemic arthritic manifestations of CM3D-treated animals. Overall, the results show that the use of UC-MSC CM3D is a viable and better strategy than direct UC-MSC administration for counteracting AIA-related signs. This strategy represents a novel MSC-based but nonetheless cell-free treatment for arthritic conditions such as those characterising RA.

Identification of Myocardial Telocytes and Bone Marrow Mesenchymal Stem Cells in Mice

OBJECTIVES

The aim of this study was to compare the morphology, immune phenotype, and cytokine profiles between myocardial telocytes (TCs) and bone marrow mesenchymal stem cells (MSCs), and explore the difference between those two types of interstitial cells.

METHODS

TCs and MSCs were cultured in vitro and cell morphology was observed with a light microscope. The expression levels of CD34, c-kit, and vimentin were detected by immunofluorescence, RT-qPCR, and Western blotting in both TCs and MSCs. The related supernatant was collected and total of 49 cytokine profiles were detected by RayBio Mice Cytokine Antibody Array. Significantly different cytokines were further confirmed by ELISA.

RESULTS

TCs have small cellular body and very long prolongations and they were CD34⁺/c-kit⁺/vimentin⁺, whereas MSCs have no telopodes and they were CD34^-/c-kit^- /vimentin⁺. Cytokine profile analysis and ELISA showed that 19 of 49 cytokines were increased dramatically in the supernatant of TCs compared with those of MSCs. Moreover, 9 of 19 cytokines were increased 2-fold at least in the supernatant of TCs compared with those of MSCs. Of 49 cytokines, 30 exhibited no significant changes in the supernatant of TCs compared with those of MSCs.

CONCLUSIONS

Using various technologies, we identified that myocardial TCs and MSCs are significantly different in terms of cell structure and cytokine profiles.