Comparative study of different centrifugation protocols for a density gradient separation media in isolation of osteoprogenitors from bone marrow aspirate

The Impact of Centrifugal Force on Isolation of Bone Marrow Mononuclear Cells Using Density Gradient Centrifugation

BACKGROUND

Bone marrow mononuclear cells (BMMNCs) have great potential in bone regenerative therapy. The main method used today to obtain BMMNCs is Ficoll density gradient centrifugation. However, the centrifugal force for this isolation method is still suboptimal.

OBJECTIVES

To determine the optimal centrifugal force in Ficoll density gradient centrifugation of bone marrow (BM) to achieve high stem/progenitor cell content BMMNCs for regenerative therapy.

METHODS

BM was aspirated from nine minipigs and divided into three groups according to different centrifugal forces (200 g, 300 g and 400 g). Immediately after BMMNCs were obtained from each group by Ficoll density gradient centrifugation, residual red blood cell (RBC) level, nucleated cell counting, viability and flow cytometric analyses of apoptosis and reactive oxygen species (ROS) generation were measured. The phenotypic CD90 and colony formation analyses of BMMNCs of each group were performed as well. Bone marrow-derived mesenchymal stem cells (BMSCs) were harvested at passage 2, then morphology, cell phenotype, proliferation, adipogenic, chondrogenic and osteogenic lineage differentiation potential of BMSCs from each group were compared.

RESULTS

The 300 g centrifugal force was able to isolate BMMNCs from BM with the same efficiency as 400 g and provided significantly higher yields of CD90+ BMSCs and fibroblastic colony-forming units of BMSC (CFU-f(BMSC)), which is more crucial for the regenerative efficacy of BMMNCs. Meanwhile, 200 g hosted the most RBC contamination and minimum CFU-f (BMSC) yield, which will be disadvantageous for BMMNC-based cell therapy. As for in vitro cultured BMSCs which were isolated from BMMNCs by different centrifugal forces, no significant differences were found on morphology, cell proliferation rate, phenotypic marker, adipogenic, chondrogenic and osteogenic differentiation potential.

CONCLUSIONS

300 g may be the optimal centrifugal force when using Ficoll density gradient centrifugation to isolate BMMNCs for bone regenerative therapy.

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Scalable mesenchymal stem cell enrichment from bone marrow aspirate using deterministic lateral displacement (DLD) microfluidic sorting

The growing interest in regenerative medicine has opened new avenues for novel cell therapies using stem cells. Bone marrow aspirate (BMA) is an important source of stromal mesenchymal stem cells (MSCs). Conventional MSC harvesting from BMA relies on archaic centrifugation methods, often leading to poor yield due to osmotic stress, high centrifugation force, convoluted workflow, and long experimental time (∼2-3 hours). To address these issues, we have developed a scalable microfluidic technology based on deterministic lateral displacement (DLD) for MSC isolation. This passive, label-free cell sorting method capitalizes on the morphological differences between MSCs and blood cells (platelets and RBCs) for effective separation using an inverted L-shaped pillar array. To improve throughput, we developed a novel multi-chip DLD system that can process 2.5 mL of raw BMA in 20 ± 5 minutes, achieving a 2-fold increase in MSC recovery compared to centrifugation methods. Taken together, we envision that the developed DLD platform will enable fast and efficient isolation of MSCs from BMA for effective downstream cell therapy in clinical settings.

An optimized force-triggered density gradient sedimentation method for isolation of pelage follicle dermal papilla cells from neonatal mouse skin

BACKGROUND

The dermal papilla cells are a specialized population of mesenchymal cells located at the base of the hair follicle (HF), which possess the capacity to regulate HF morphogenesis and regeneration. However, lack of cell-type specific surface markers restricts the isolation of DP cells and application for tissue engineering purposes.

METHODS

We describe a novel force-triggered density gradient sedimentation (FDGS) method to efficiently obtain purified follicular DP-spheres cells from neonatal mouse back skin, utilizing only centrifugation and optimized density gradients.

RESULTS

Expression of characteristic DP cell markers, alkaline phosphatase, β-catenin, versican, and neural cell adhesion molecules, were confirmed by immunofluorescence. Further, the patch assays demonstrated that DP cells maintained their hair regenerative capacity in vivo. Compared with current methods, including microdissection and fluorescence-activated cell sorting, the FDGS technique is simpler and more efficient for isolating DP cells from neonatal mouse skin.

CONCLUSIONS

The FDGS method will improve the research potential of neonatal mouse pelage-derived DP cells for tissue engineering purposes.

Cell surface markers for mesenchymal stem cells related to the skeletal system: A scoping review

Multipotent mesenchymal stromal cells (MSCs) have been described as bone marrow stromal cells, which can form cartilage, bone or hematopoietic supportive stroma. In 2006, the International Society for Cell Therapy (ISCT) established a set of minimal characteristics to define MSCs. According to their criteria, these cells must express CD73, CD90 and CD105 surface markers; however, it is now known they do not represent true stemness epitopes. The objective of the present work was to determine the surface markers for human MSCs associated with skeletal tissue reported in the literature (1994-2021). To this end, we performed a scoping review for hMSCs in axial and appendicular skeleton. Our findings determined the most widely used markers were CD105 (82.9%), CD90 (75.0%) and CD73 (52.0%) for studies performed in vitro as proposed by the ISCT, followed by CD44 (42.1%), CD166 (30.9%), CD29 (27.6%), STRO-1 (17.7%), CD146 (15.1%) and CD271 (7.9%) in bone marrow and cartilage. On the other hand, only 4% of the articles evaluated in situ cell surface markers. Even though most studies use the ISCT criteria, most publications in adult tissues don't evaluate the characteristics that establish a stem cell (self-renewal and differentiation), which will be necessary to distinguish between a stem cell and progenitor populations. Collectively, MSCs require further understanding of their characteristics if they are intended for clinical use.

Intraoperative Creation of Tissue-Engineered Grafts with Minimally Manipulated Cells: New Concept of Bone Tissue Engineering In Situ

Transfer of regenerative approaches into clinical practice is limited by strict legal regulation of in vitro expanded cells and risks associated with substantial manipulations. Isolation of cells for the enrichment of bone grafts directly in the Operating Room appears to be a promising solution for the translation of biomedical technologies into clinical practice. These intraoperative approaches could be generally characterized as a joint concept of tissue engineering in situ. Our review covers techniques of intraoperative cell isolation and seeding for the creation of tissue-engineered grafts in situ, that is, directly in the Operating Room. Up-to-date, the clinical use of tissue-engineered grafts created in vitro remains a highly inaccessible option. Fortunately, intraoperative tissue engineering in situ is already available for patients who need advanced treatment modalities.

Impact of the Process Variables on the Yield of Mesenchymal Stromal Cells from Bone Marrow Aspirate Concentrate

Human bone marrow (BM) has been highlighted as a promising source of mesenchymal stromal cells (MSCs) containing various growth factors and cytokines that can be potentially utilized in regenerative procedures involving cartilage and bone. However, the proportion of MSCs in the nucleated cell population of BM is only around 0.001% to 0.01% thereby making the harvesting and processing technique crucial for obtaining optimal results upon its use in various regenerative processes. Although several studies in the literature have given encouraging results on the utility of BM aspiration concentrate (BMAC) in various regenerative procedures, there is a lack of consensus concerning the harvesting variables such as choice of anesthetic agent to be used, site of harvest, size of the syringe to be used, anticoagulant of choice, and processing variables such as centrifugation time, and speed. In this review article, we aim to discuss the variables in the harvesting and processing technique of BMAC and their impact on the yield of MSCs in the final concentrate obtained from them.

IL-12Rβ1 deficiency corresponding to concurrency of two diseases, mendelian susceptibility to mycobacterial disease and Crohn's disease

Background

The interleukin-12 receptor β1 (IL-12Rβ1) deficiency is a primary immunodeficiency (PID), affecting the immunological pathway of interleukin 12/interferon- γ (IL12/IFN-γ) axis and interleukin 23 receptor (IL23R). Defect in this pathway is mainly affecting the cellular immunity-related disorders. IL-12Rβ1 is a receptor chain of both the IL-12 and the IL-23 receptors and thus, deficiency of IL-12Rβ1 abolishes both IL-12 and IL-23 signaling.

Material and methods

In this study, we performed whole exon sequencing and confirmatory Sanger sequencing in IL-12Rβ1. Evaluation of the IL12/IFN-γ axis was performed by assessment of patients’ whole blood cell to IL12/IFN-γ responding. Total and surface IL-12Rβ1expression was evaluated, in peripheral blood mononuclear cells (PBMCs) and T cell- derived PBMCs, and Th17 count was assessed.

Results

In the present study, we described a c.1791 + 2T > G mutation at a splicing site position in IL-12Rβ1, using whole exome sequencing, and confirmed with targeted Sanger sequencing in a 26- year-old patient with Mendelian susceptibility to mycobacterial disease (MSMD) and Crohn's disease (CD). Complete lack of IL-12Rβ1 protein expression was detected in patient's PBMCs, compared to the healthy control. Furthermore, no IL-12Rβ1 protein was expressed on the cell surface. Interestingly, IL-12Rβ1-mutant cells showed an impaired response to IL12, and Bacillus Calmette–Guérin stimulation, confirming that the mutation is causative in this patient.

Conclusion

A 3′splicing site mutation in IL12Rβ1, can be corresponding to the abolished expression of IL12Rβ1 in patients' cells, and associated with an impaired IL12-mediated signaling, which may lead not only to MSMD, but also to inflammatory bowel disease (IBD).

Osteoblast studied on gelatin based biomaterials in rabbit Bone Bioengineering

The bone-derived-osteoblast seeded biomaterials scaffold in tissue engineering, have displayed prominence in the treatment of the osseous medical condition. In vitro osteogenesis of rabbit osteoblast cell (rOb) from bone tissue (rT) and MSC-derived rOb from bone marrow (rM) on Gelatin-Hydroxyapatite (HG) based biomaterials was investigated. In this work, lyophilized biomaterial was prepared by the addition of amorphous chitosan ('C') to 'H' dispersed in 'G' matrix, to find its role in biomaterials biocompatibility. Isolated rOb seeded biomaterials were studied using CLSM and flow cytometry for proliferation potential. The biomaterial's core and surface morphology was studied from SEM-EDX and AFM respectively. Upon co-culture with HCG, rT over rM showed rabbit bone extracellular matrix (ECM) mimicking properties both in in vitro studies and biomaterials micro architecture. The in vitro metabolic behaviour was studied by Alamar Blue (AB) assay, DNA content using Hoechst 33258, potency via the activity of Alkaline Phosphatase (ALP), Calcium's relative content by Alizarin Red S (ARS) assay. A novel combination of biomaterials-cell interaction was observed when rT was co-cultured with HCG and proved effective in osteogenesis with regard to Bone Bioengineering.

In vitro studies on gelatin/hydroxyapatite composite modified with osteoblast for bone bioengineering

A promising route towards bone tissue engineering is made by the raw materials of the composite which mimics properties of the extracellular matrix components. Herein, the favourable human origin bone cells were seeded on the scaffold types to investigate the best co-culture system. The same has been achieved after the synthesis and characterization of gelatin/hydroxyapatite composites infused with chitosan for their calcium to phosphate (Ca/P) ratio by SEM-EDX. Also, in vitro biodegradation and bio-mineralization determined after immersing in lysozyme and SBF respectively. Uni-axial Compressive Strength (UCS), porosity, qualitative to quantitative phase development by XRD and FTIR were evaluated. The human bone cell-seeded composite was tested by flow cytometry, CLSM, SEM and DSC. This study statistically signified the human mesenchymal stem cell (hM) derived bone cell as potential raw material for minor to severe bone related tissue regenerative studies.

Modeling biological and economic uncertainty on cell therapy manufacturing: the choice of culture media supplementation

AIM

To evaluate the cost-effectiveness of autologous cell therapy manufacturing in xeno-free conditions.

MATERIALS & METHODS

Published data on the isolation and expansion of mesenchymal stem/stromal cells introduced donor, multipassage and culture media variability on cell yields and process times on adherent culture flasks to drive cost simulation of a scale-out campaign of 1000 doses of 75 million cells each in a 400 square meter Good Manufacturing Practices facility.

RESULTS & CONCLUSION

Passage numbers in the expansion step are strongly associated with isolation cell yield and drive cost increases per donor of $1970 and 2802 for fetal bovine serum and human platelet lysate. Human platelet lysate decreases passage numbers and process costs in 94.5 and 97% of donors through lower facility and labor costs. Cost savings are maintained with full equipment depreciation and higher numbers of cells per dose, highlighting the number of cells per passage step as the key cost driver.

Assessment of Methods for Rapid Intraoperative Concentration and Selection of Marrow-Derived Connective Tissue Progenitors for Bone Regeneration Using the Canine Femoral Multidefect Model

Treatment of large bone defects remains an unsolved clinical challenge, despite a wide array of existing bone graft materials and strategies. Local deficiency in osteogenic connective tissue progenitors (CTP-Os) due to tissue loss is one of the central biological barriers to bone regeneration. Density separation (DS) and selective retention (SR) represent two promising methods that can be used intraoperatively to rapidly concentrate cells and potentially select CTP-Os. This project was designed to compare DS and SR using the canine femoral multidefect (CFMD) model. Mineralized cancellous allograft (MCA) was used as a standardized scaffold for cell transplantation. Two experiments were performed using a cohort of six animals in each comparison. In Cohort I, unprocessed bone marrow aspirate (BMA) clot was compared to DS processing. MCA combined with raw BMA or DS processed cells produced a robust and advanced stage of bone regeneration throughout the defect in 4 weeks with reconstitution of hematopoietic marrow. However, the retention of DS processed cells and CTP-Os in the MCA matrix was low compared to BMA clot. In Cohort II, MCA with DS-T cells (addition of calcium chloride thrombin to induce clotting and enhance cell and CTP-O retention) was compared to MCA with SR cells. A mean of 276 ± 86 million nucleated cells and 29,030 ± 10,510 CTP-Os were implanted per defect in the DS-T group. A mean of 76 ± 42 million nucleated cells and 30,266 ± 15,850 CTP-Os were implanted in the SR group. Bone formation was robust and not different between treatments. Histologically, both groups demonstrated regeneration of hematopoietic marrow tissue. However, SR sites contained more hematopoietic vascular tissues, less fibrosis, and less residual allograft, particularly in the intramedullary cavity, suggesting a more advanced stage of remodeling (p = 0.04). These data demonstrate excellent overall performance of DS and SR processing methods. Both methods achieve a bone regeneration response that approaches the limits of performance that can be achieved in the CFMD model. Further advancement and comparison of these intraoperative bone marrow cell processing methods will require use of a larger and more biologically compromised defect site to guide the next steps of preclinical development and optimization.