Bone Formation by Sheep Stem Cells in an Ectopic Mouse Model: Comparison of Adipose and Bone Marrow Derived Cells and Identification of Donor-Derived Bone by Antibody Staining

Osteogenic capacity of mesenchymal stem cells from patients with osteoporotic hip fractures in vivo

PURPOSE

Human mesenchymal stem cells (MSCs) have the ability to differentiate into bone-forming osteoblasts. The aim of this study was to elucidate if MSCs from patients with OP show a senescent phenotype and explore their bone-forming ability in vivo.

MATERIALS AND METHODS

MSCs from patients with OP and controls with osteoarthritis (OA) were implanted into the subcutaneous tissue of immunodeficient mice for histological analysis and expression of human genes by RT-PCR. The expression of senescence-associated phenotype (SASP) genes, as well as p16, p21, and galactosidase, was studied in cultures of MSCs.

RESULTS

In vivo bone formation was evaluated in 103 implants (47 OP, 56 OA). New bone was observed in 45% of the implants with OP cells and 46% of those with OA cells (p = 0.99). The expression of several bone-related genes (collagen, osteocalcin, alkaline phosphatase, sialoprotein) was also similar in both groups. There were no differences between groups in SASP gene expression, p16, and p21 expression, or in senescence-associated galactosidase activity.

CONCLUSION

Senescence markers and the osteogenic capacity in vivo of MSCs from patients with OP are not inferior to that of cells from controls of similar age with OA. This supports the interest of future studies to evaluate the potential use of autologous MSCs from OP patients in bone regeneration procedures.

Clinical Applications of Cell-Scaffold Constructs for Bone Regeneration Therapy

Bone tissue engineering (BTE) is a process of combining live osteoblast progenitors with a biocompatible scaffold to produce a biological substitute that can integrate into host bone tissue and recover its function. Mesenchymal stem cells (MSCs) are the most researched post-natal stem cells because they have self-renewal properties and a multi-differentiation capacity that can give rise to various cell lineages, including osteoblasts. BTE technology utilizes a combination of MSCs and biodegradable scaffold material, which provides a suitable environment for functional bone recovery and has been developed as a therapeutic approach to bone regeneration. Although prior clinical trials of BTE approaches have shown promising results, the regeneration of large bone defects is still an unmet medical need in patients that have suffered a significant loss of bone function. In this present review, we discuss the osteogenic potential of MSCs in bone tissue engineering and propose the use of immature osteoblasts, which can differentiate into osteoblasts upon transplantation, as an alternative cell source for regeneration in large bone defects.

Vascular Endothelial Growth Factor and Mesenchymal Stem Cells Revealed Similar Bone Formation to Allograft in a Sheep Model

Introduction

Mesenchymal stem cells (MSCs) and vascular endothelial growth factor (VEGF) are key factors in bone regeneration. Further stimulation should establish an enhanced cell environment optimal for vessel evolvement and hereby being able to attract bone-forming cells. The aim of this study was to generate new bone by using MSCs and VEGF, being able to stimulate growth equal to allograft.

Methods

Eight Texel/Gotland sheep had four titanium implants in a size of 10 × 12 mm inserted into bilateral distal femurs, containing a 2 mm gap. In the gap, autologous 3 × 10⁶ MSCs seeded on hydroxyapatite (HA) granules in combination with 10 ng, 100 ng, and 500 ng VEGF release/day were added. After 12 weeks, the implant-bone blocks were harvested, embedded, and sectioned for histomorphometric analysis. Bone formation and mechanical fixation were evaluated. Blood samples were collected for the determination of bone-related biomarkers and VEGF in serum at weeks 0, 1, 4, 8, and 12.

Results

The combination of 3 × 10⁶ MSCs with 10 ng, 100 ng, and 500 ng VEGF release/day exhibited similar amount of bone formation within the gap as allograft (P > 0.05). Moreover, no difference in mechanical fixation was observed between the groups (P > 0.05). Serum biomarkers showed no significant difference compared to baseline (all P > 0.05).

Conclusion

MSCs and VEGF exhibit significant bone regeneration, and their bone properties equal to allograft, with no systemic increase in osteogenic markers or VEGF with no visible side effects. This study indicates a possible new approach into solving the problem of insufficient allograft, in larger bone defects.

Comparisons of Efficacy between Autograft and Allograft on Defect Repair In Vivo in Normal and Osteoporotic Rats

Introduction. In the field of orthopaedic surgery, the use of osteogenic material in larger defects is essential. Autograft and allograft are both known methods, and autograft is believed to be the best choice. But autograft is associated with additional invasive procedures which can prove difficult in fragile patients and can cause local side effect after bone harvest. For feasible purposes, the use of allograft is hereby rising and comparing efficacies, and the differences between autograft and allograft are essential for the clinical outcome for the patients.

Material-Induced Venosome-Supported Bone Tubes

The development of alternatives to vascular bone grafts, the current clinical standard for the surgical repair of large segmental bone defects still today represents an unmet medical need. The subcutaneous formation of transplantable bone has been successfully achieved in scaffolds axially perfused by an arteriovenous loop (AVL) and seeded with bone marrow stromal cells or loaded with inductive proteins. Although demonstrating clinical potential, AVL-based approaches involve complex microsurgical techniques and thus are not in widespread use. In this study, 3D-printed microporous bioceramics, loaded with autologous total bone marrow obtained by needle aspiration, are placed around and next to an unoperated femoral vein for 8 weeks to assess the effect of a central flow-through vein on bone formation from marrow in a subcutaneous site. A greater volume of new bone tissue is observed in scaffolds perfused by a central vein compared with the nonperfused negative control. These analyses are confirmed and supplemented by calcified and decalcified histology. This is highly significant as it indicates that transplantable vascularized bone can be grown using dispensable vein and marrow tissue only. This is the first report illustrating the capacity of an intrinsic vascularization by a single vein to support ectopic bone formation from untreated marrow.

Optimizing Osteogenic Differentiation of Ovine Adipose-Derived Stem Cells by Osteogenic Induction Medium and FGFb, BMP2, or NELL1 In Vitro

Although adipose-derived stromal cells (ADSCs) have been a major focus as an alternative to autologous bone graft in orthopedic surgery, bone formation potential of ADSCs is not well known and cytokines as osteogenic inducers on ADSCs are being investigated. This study aimed at isolating ADSCs from ovine adipose tissue (AT) and optimizing osteogenic differentiation of ovine ADSCs (oADSC) by culture medium and growth factors. Four AT samples were harvested from two female ovine (Texel/Gotland breed), and oADSCs were isolated and analyzed by flow cytometry for surface markers CD29, CD44, CD31, and CD45. Osteogenic differentiation was made in vitro by seeding oADSCs in osteogenic induction medium (OIM) containing fibroblast growth factor basic (FGFb), bone morphogenetic protein 2 (BMP2), or NEL-like molecule 1 (NELL1) in 4 different dosages (1, 10, 50, and 100 ng/ml, respectively). Basic medium (DMEM) was used as control. Analysis was made after 14 days by Alizarin red staining (ARS) and quantification. This study successfully harvested AT from ovine and verified isolated cells for minimal criteria for adipose stromal cells which suggests a feasible method for isolation of oADSCs. OIM showed significantly higher ARS to basic medium, and FGFb 10 ng/ml revealed significantly higher ARS to OIM alone after 14 days.

Optimizing combination of vascular endothelial growth factor and mesenchymal stem cells on ectopic bone formation in SCID mice

INTRODUCTION

Insufficient blood supply may limit bone regeneration in bone defects. Vascular endothelial growth factor (VEGF) promotes angiogenesis by increasing endothelial migration. This outcome, however, could depend on time of application. Sheep mesenchymal stem cells (MSCs) in severe combined immunodeficient (SCID) mice were used in this study to evaluate optimal time points for VEGF stimulation to increase bone formation.

METHODS

Twenty-eight SCID (NOD.CB17-Prkdc^scid /J) mice had hydroxyapatite granules seeded with 5 × 10⁵ MSCs inserted subcutaneous. Pellets released VEGF on days 1-7, days 1-14, days 1-21, days 1-42, days 7-14, and days 21-42. After 8 weeks, the implant-bone-blocks were harvested, paraffin embedded, sectioned, and stained with both hematoxylin and eosin (HE) and immunohistochemistry for human vimentin (hVim) staining. Blood samples were collected for determination of bone-related biomarkers in serum.

RESULTS

The groups with 5 × 10⁵ MSCs and VEGF stimulation on days 1-14 and days 1-21 showed more bone formation when compared to the control group of 5 × 10⁵ MSCs alone (p < 0.01). Serum biomarkers had no significant values. The hVim staining confirmed the ovine origin of the observed ectopic bone formation.

CONCLUSION

Optimal bone formation of MSCs was reached when stimulating with VEGF during the first 14 or 21 days after surgery. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3326-3332, 2017.