Gene therapy in orthopaedics

Orthopedic Research Funding: Assessing the Relationship between Investments and Breakthroughs

Orthopedic research plays a crucial role in improving patient outcomes for musculoskeletal disorders. This narrative review explores the intricate interplay between funding patterns and the trajectory of breakthroughs achieved in this dynamic field. A meticulous search strategy identified studies illuminating the diverse sources of orthopedic research funding, including public funding (government agencies), philanthropic organizations, private sector investment, and international funding bodies. The review further delved into the spectrum of breakthroughs, encompassing fundamental scientific discoveries, technological advancements, and personalized medicine approaches. Public funding emerged as a significant pillar, supporting foundational research that lays the groundwork for future advancements. Philanthropic organizations addressed specific musculoskeletal disorders, often focusing on patient-centric applications. International funding bodies played a role in supporting research in low- and middle-income countries. Breakthroughs extended beyond cutting-edge prosthetics and minimally invasive surgeries, encompassing fundamental discoveries in areas like gene therapy and biomaterials science. Technological advancements included brain-computer interface prosthetics and 3D-printed implants. Personalized medicine offered the potential for tailored treatments based on individual needs and genetic profiles. This review underscores the complex interplay between funding patterns and breakthroughs in orthopedic research. A multifaceted approach is essential for continued progress. Fostering collaboration, optimizing funding models, and prioritizing both foundational and translational research hold the key to unlocking the true potential of orthopedic research and transforming the lives of patients suffering from musculoskeletal disorders.

Efficacy of mesoporous silica nanoparticles in delivering BMP-2 plasmid DNA for in vitro osteogenic stimulation of mesenchymal stem cells

We report the ability of aminated mesoporous silica nanoparticles (MSN-NH2) with large mesopore space and positive-charged surface to deliver genes within rat mesenchymal stem cells (MSCs). The amine functionalized inorganic nanoparticles were complexed with bone morphogenetic protein-2 (BMP2) plasmid DNA (pDNA) to study their transfection efficiency in MSCs. Intracellular uptake of the complex BMP2 pDNA/MSN-NH2 occurred significantly, with a transfection efficiency of approximately 68%. Furthermore, over 66% of the transfected cells produced BMP2 protein. The osteogenic differentiation of the transfected MSCs was demonstrated by the expression of bone-related genes and proteins including bone sialoprotein, osteopontin, and osteocalcin. The MSN-NH2 delivery vehicle for BMP2 pDNA developed in this study may be a potential gene delivery system for bone tissue regeneration.

Genetically-manipulated adult stem cells as therapeutic agents and gene delivery vehicle for wound repair and regeneration

Wound therapy remains a clinical challenge and much effort has been focused on the development of novel therapeutic approaches for wound management. New knowledge about the way in which signals control wound cellular and molecular behavior has promoted the topical application of multipotent stem cells and bioactive molecules to injured tissue, for skin regeneration with less scar formation. However, limited clinical success indicates that the effective delivery of polypeptides and therapeutic cells, with controlled releasing profile, is a major challenge which is yet to be overcome. Recently, a technique in which the genetically-manipulated stem cells were used both as the therapeutic agents and the vehicle for gene delivery for wound treatment - a method which serves to provide regenerative cells and bioactive genes within an optimal environment of regulatory molecular expression for wound sites - has emerged as a promising strategy for wound regenerative therapy. In this article, the roles of adult stem cells - as the therapeutics and the vehicles in these advanced biomimetic drug delivery systems for wound regeneration medicine - are scrutinized to indicate their mechanisms, characteristics, broad applicability and future lines of investigation.

In vitro evaluation of a double-stranded self-complementary adeno-associated virus type2 vector in bone marrow stromal cells for bone healing

BACKGROUND

Both adenoviral and lentiviral vectors have been successfully used to induce bone repair by over-expression of human bone morphogenetic protein 2 (BMP-2) in primary rat bone marrow stromal cells in pre-clinical models of ex vivo regional gene therapy. Despite being a very efficient means of gene delivery, there are potential safety concerns that may limit the adaptation of these viral vectors for clinical use in humans. Recombinant adeno-associated viral (rAAV) vector is a promising viral vector without known pathogenicity in humans and has the potential to be an effective gene delivery vehicle to enhance bone repair. In this study, we investigated gene transfer in rat and human bone marrow stromal cells in order to evaluate the effectiveness of the self-complementary AAV vector (scAAV) system, which has higher efficiency than the single-stranded AAV vector (ssAAV) due to its unique viral genome that bypasses the rate-limiting conversion step necessary in ssAAV.

METHODS

Self-complementaryAAV2 encoding GFP and BMP-2 (scAAV2-GFP and scAAV2-BMP-2) were used to transduce human and rat bone marrow stromal cells in vitro, and subsequently the levels of GFP and BMP-2 expression were assessed 48 hours after treatment. In parallel experiments, adenoviral and lentiviral vector mediated over-expression of GFP and BMP-2 were used for comparison.

RESULTS

Our results demonstrate that the scAAV2 is not capable of inducing significant transgene expression in human and rat bone marrow stromal cells, which may be associated with its unique tropism.

CONCLUSIONS

In developing ex vivo gene therapy regimens, the ability of a vector to induce the appropriate level of transgene expression needs to be evaluated for each cell type and vector used.

Enhancing allograft bone healing through gene therapy

STUDY DESIGN

A review and synopsis of recent literature pertinent to allograft bone healing.

OBJECTIVE

To review the basic principles and primary issues regarding the healing of allograft bone. To review progress made in understanding the molecular mechanisms of healing, and efforts being made to manipulate these processes to enhance healing.

SUMMARY OF BACKGROUND DATA

Bone grafting with both autografts and allografts is a common reconstructive procedure. Failure to heal and catastrophic failure of seemingly healed structural grafts occur. There is currently a great deal of excitement about the potential of bone marrow-derived cells to enhance healing. Gene transfer techniques have been developed which allow the insertion of desired deoxyribonucleic acid-encoded messages into cells. Such messages can result in the production of therapeutic proteins. Gene therapy has been used to enhance the healing of allografts in a murine model.

METHODS

Literature review.

RESULTS

Autografts heal by endochondral ossification at the graft-host interface and by intramembranous bone formation over the surface of the graft. Allografts heal predominately by endochondral ossification at the graft-host interface. The living periosteum of a graft contains progenitor cells that have an important role in graft healing. The addition of bone marrow-derived cells to an allograft does not improve healing unless they are genetically modified to express bone morphogenetic protein 2. Gene therapy to induce expression of several other proteins (VEGF and RANKL, caALK2) can also result in markedly improved allograft healing.

CONCLUSION

Gene therapy techniques can create revitalized allografts in a mouse model. These revitalized grafts heal faster, more completely, more durably, and stronger than allografts.

Accelerated Achilles tendon healing by PDGF gene delivery with mesoporous silica nanoparticles

We report the ability of amino- and carboxyl-modified MCM-41 mesoporous silica nanoparticles (MSN) to deliver gene in vivo in rat Achilles tendons, despite their inefficiency to transfect primary tenocytes in culture. We show that luciferase activity lasted for at least 2 weeks in tendons injected with these MSN and a plasmid DNA (pDNA) encoding the luciferase reporter gene. By contrast, in tendons injected with naked plasmid, the luciferase expression decreased as a function of time and became hardly detectable after 2 weeks. Interestingly, there were neither signs of inflammation nor necrosis in tendon, kidney, heart and liver of rat weekly injected with pDNA/MSN formulation during 1.5 months. Our main data concern the acceleration of Achilles tendons healing by PDGF-B gene transfer using MSN. Biomechanical properties and histological analyses clearly indicate that tendons treated with MSN and PDGF gene healed significantly faster than untreated tendons and those treated with pPDGF alone.

Biological activation of bone-related biomaterials by recombinant adeno-associated virus vector

Gene therapy is a promising clinical tool that is no longer limited as a method to supplement genetic deficits, but rather is considered reliable for delivering proteins to specific tissues or cells. Recombinant adeno-associated virus (rAAV) vector is one of the most potent gene transfer vehicles. Many biomaterials have been used in reconstructive surgery, but their biological inactivity has limited their use. To overcome shortcomings of available bone-related biomaterials, we investigated the combination of rAAV with biomaterials. Taking advantage of the method of lyophilizing rAAV onto biomaterials, we showed that an rAAV coating successfully induced beta-galactosidase protein expression by rat fibroblasts on hydroxyapatite, beta-tricalcium phosphate, and titanium alloy in vitro. beta-Galactosidase expression was detected for 8 weeks after implantation of rAAV-coated hydroxyapatite into rat back muscles in vivo. A coating of bone morphogenetic protein-2-expressing rAAV induced significant de novo bone formation on hydroxyapatite in rat back muscles. Our study demonstrates that the combination of lyophilized rAAV and biomaterials presents a promising strategy for bone regenerative medicine.

Fracture healing and bone repair: an update

Bone healing represents a physiological process of repair and restoration of function. Recent advances in a variety of medical disciplines have enabled scientists and clinicians to characterise this phenomenon at the molecular level. A number of molecular mediators and cells interact utilising different pathways. Despite the involvement of many local and systemic factors failure of the naturally occurring mechanisms can occur leading to either delayed union or non-union. This review article is focused on the recent understanding of the mechanisms governing the bone repair process.

Cell therapy for bone regeneration--bench to bedside

The concept of bone tissue engineering, which began in the early 1980s, has seen tremendous growth in the numbers of research studies. One of the key areas of research has been in the field of mesenchymal stem cells, where the challenge is to produce the perfect tissue-engineered bone construct. This practical review summarizes basic and applied state-of-the-art research in the area of mesenchymal stem cells, and highlights the important translational research that has already been initiated. The topics that will be covered include the sources of stem cells in use, scaffolds, gene therapy, clinical applications in nonunions, tumors, osteonecrosis, revision arthroplasties, and spine fusion. Although significant challenges remain, there exists an exceptional opportunity to translate basic research in mesenchymal stem cell technologies into viable clinical treatments for bone regeneration.

Global burden of trauma: Need for effective fracture therapies

Orthopedic trauma care and fracture management have advanced significantly over the last 50 years. New developments in the biology and biomechanics of the musculoskeletal system, fixation devices, and soft tissue management have greatly influenced our ability to care for musculoskeletal injuries. Many therapies and treatment modalities have the potential to transform future orthopedic treatment by decreasing invasive procedures and providing shorter healing times. Promising results in experimental models have led to an increase in clinical application of these therapies in human subjects. However, for many modalities, precise clinical indications, timing, dosage, and mode of action still need to be clearly defined. In order to further develop fracture management strategies, predict outcomes and improve clinical application of newer technologies, further research studies are needed. Together with evolving new therapies, the strategies to improve fracture care should focus on cost effectiveness. This is a great opportunity for the global orthopedic community, in association with other stakeholders, to address the many barriers to the delivery of safe, timely, and effective care for patients with musculoskeletal injuries in developing countries.

Percutaneous nonviral delivery of hepatocyte growth factor in an osteotomy gap promotes bone repair in rabbits: a preliminary study

Hepatocyte growth factor (HGF) was initially identified in cultured hepatocytes and subsequently reported to induce angiogenic, morphogenic, and antiapoptotic activity in various tissues. These properties suggest a potential influence of HGF on bone healing. We asked if gene transfer of human HGF (hHGF) into an osteotomy gap with a hemagglutinating virus of Japan-envelope (HVJ-E) vector promotes bone healing in rabbits. HVJ-E that contained either hHGF or control plasmid was percutaneously injected into the osteotomy gap of rabbit tibias on Day 14. The osteotomy gap was evaluated by radiography, pQCT, mechanical tests, and histology at Week 8. The expression of hHGF was evaluated by reverse transcriptase-polymerase chain reaction and immunohistochemistry at Week 3. Radiography, pQCT, and histology suggested the hHGF group had faster fracture healing. Mechanical tests demonstrated the hHGF group had greater mechanical strength. The injected tissues at 3 weeks expressed hHGF mRNA by reverse transcriptase-polymerase chain reaction. hHGF-positive immunohistochemical staining was observed in various cells at the osteotomy gap at Week 3. The data suggest delivery of hHGF plasmid into the osteotomy gap promotes fracture repair, and HGF could become a novel agent for fracture treatment.

Fracture vascularity and bone healing: a systematic review of the role of VEGF

Fracture healing constitutes a complex and delicate physiological process. Local vascularity at the site of the fracture has been identified as one of the most significant parameters influencing the healing procedure. VEGF is the most important component of the regeneration of the vascular system at the fracture site. The aim of this review is to determine the evidence supporting the direct role of VEGF in the enhancement of fracture healing and the possible clinical use of VEGF for non-unions. The literature search was performed via the internet using the Medline. The key words which were searched in the abstracts were the terms "VEGF", "angiogenesis", "fracture", "bone" and "healing". Twenty-five articles were relevant to the topic of interest. A total of 11 articles were excluded from our research due to non conformity of their content to the inclusion criteria. Evidence retrieved suggests that VEGF could be extremely valuable for the treatment of critical size bone defects and that VEGF could have a direct effect on osteoprogenitor cells, mainly by promoting the differentiation of osteoblasts and by increasing the mineralisation of the regenerated bone. The former observation could have very interesting repercussions for the field of non-unions and the latter for the field of osteoporosis.

Critical analysis of the evidence for current technologies in bone-healing and repair

Substances that enhance fracture-healing and bone regeneration have valuable clinical application and merit future research. Advances in these technologies will enhance our ability to heal fractures in a more effective and expedient manner. This review provides a brief description of the different techniques and technologies and their respective clinical utility. This paper also reviews the available literature on gene therapy, tissue engineering, growth factors, osteoconductive agents, and physical forces and assesses the evidence regarding the current status of these techniques of healing and regenerating bone. Only twenty-seven articles met our guidelines for studies containing Level-I evidence. We were able to determine that atrophic nonunions and pseudarthrosis led to poorer outcomes, and the results were uniformly poor irrespective of the technique used. Although the literature contains a large number of studies on the effects of different agents and modalities on bone repair and healing, it still is not clear how these agents work or in what circumstances they should be used. Many of the treatment modalities of interest are still at an experimental stage, so good evidence to support clinical practice is lacking. Additional multicenter, prospective randomized studies are needed to define the indications, specifications, dosage, limitations, and contraindications in the treatment of nonunions. Studies are also needed to address the full clinical feasibility of the role of each modality in fracture-healing and repair.