Improving bone repair of femoral and radial defects in rabbit by incorporating PRP into PLGA/CPC composite scaffold with unidirectional pore structure

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Electrospun sandwich mesh structures loaded with naringenin and vitamin K2 polycaprolactone/gelatin nanofibers synergistically promote bone regeneration

Osteoblasts and osteoclasts play a crucial role in the dynamically coupled balance during bone regeneration and remodeling. They complement and restrict each other in the human body. Decreased osteoblasts lead to insufficient bone formation or excessive formation of osteoclasts, leading to increased bone resorption, which will destroy the structure of the bone tissue. This will greatly increase the risk of diseases such as osteoporosis and nonunions caused by bone defects. Herein, gelatin and polycaprolactone were used as substrates, and biomaterial membranes with mesh and sandwich structures were constructed using the electrospinning technology. Naringenin was loaded into the shell, and vitamin K2 was loaded into the core layer of the nanofibrous membrane. The biocompatibility and osteogenic capacity of the membranes were assessed in vitro using mouse bone marrow mesenchymal stem cells (BMSCs). During osteoclast induction, the receptor activator of nuclear factor kappa-Β ligand (RANKL) was used to coculture RAW264.7 cells with various materials. The regulatory effect of various membranes on osteoclast growth was evaluated by detecting the expression levels of osteoclast-related genes and proteins in the cells. Subsequently, we constructed a model of a rat skull defect and implanted different membranes into the defect. Then, we evaluated the new bone formation in the defect using histological staining and micro-computed tomography after 4 and 8 weeks. The results of in vitro experiments confirmed that the incorporation of naringenin and vitamin K2 stimulated the expression of osteogenesis-related genes and the secretion of osteogenesis-related proteins. Simultaneously, the results showed that naringenin and vitamin K2 inhibited the formation and growth of osteoclasts. Therefore, naringenin and vitamin K2 have a synergistic effect in promoting bone growth and regulating osteoclast growth.

Aligned Ice Templated Biomaterial Strategies for the Musculoskeletal System

Aligned pore structures present many advantages when conceiving biomaterial strategies for treatment of musculoskeletal disorders. Aligned ice templating (AIT) is one of the many different techniques capable of producing anisotropic porous scaffolds; its high versatility allows for the formation of structures with tunable pore sizes, as well as the use of many different materials. AIT has been found to yield improved compressive properties for bone tissue engineering (BTE), as well as higher tensile strength and optimized cellular alignment and proliferation in tendon and muscle repair applications. This review evaluates the work that has been done in the last decade toward the production of aligned pore structures by AIT with an outlook on the musculoskeletal system. This work describes the fundamentals of the AIT technique and focuses on the research carried out to optimize the biomechanical properties of scaffolds by modifying the pore structure, categorizing by material type and application. Related topics including growth factor incorporation into AIT scaffolds, drug delivery applications, and studies about immune system response will be discussed.

[Recombinant human bone morphogenetic protein 2/porous calcium phosphate cement/autologous bone and combination of platelet-rich plasma in repairing of large bone defects in rabbits by Masquelet technique]

Objective

To investigate the optimal mixing ratio of recombinant human bone morphogenetic protein 2 (rhBMP-2) with porous calcium phosphate cement (PCPC) and autologous bone as bone grafting material for the repair of large bone defects using Masquelet technique. The effect of platelet-rich plasma (PRP) on the healing of bone defects was evaluated under the optimal ratio of mixed bone.

Methods

Fifty-four New Zealand White rabbits were taken to establish a 2 cm long bone defect model of the ulna and treated using the Masquelet technique. Two parts of the experiment were performed in the second phase of the Masquelet technique. First, 36 modeled experimental animals were randomly divided into 4 groups ( n=9) according to the mass ratio of autologous bone and rhBMP-2/PCPC. Group A: autologous bone (100%); group B: 25% autologous bone+75% rhBMP-2/PCPC; group C: 50% autologous bone+50% rhBMP-2/PCPC; group D: 75% autologous bone+25% rhBMP-2/PCPC. The animals were executed at 4, 8, and 12 weeks postoperatively for general observation, imaging observation, histological observation (HE staining), alkaline phosphatase (ALP) activity assay, and biomechanical assay (three-point bending test) were performed to assess the osteogenic ability and to determine the optimal mixing ratio. Then, 18 modeled experimental animals were randomly divided into 2 groups ( n=9). The control group was implanted with the optimal mixture ratio of autologous bone+rhBMP-2/PCPC, and the experimental group was implanted with the optimal mixture ratio of autologous bone+rhBMP-2/PCPC+autologous PRP. The same method was used to observe the above indexes at 4, 8, and 12 weeks postoperatively.

Results

The bone healing process from callus formation to the cortical connection at the defected gap could be observed in each group after operation; new bone formation, bridging with the host bone, and bone remodeling to normal bone density were observed on imaging observation; new woven bone, new capillaries, bone marrow cavity, and other structures were observed on histological observation. The ALP activity of each group gradually increased with time ( P<0.05); the ALP activity of group A was significantly higher than that of the other 3 groups at each time point after operation, and of groups C and D than group B ( P<0.05); there was no significant difference between groups C and D ( P>0.05). Biomechanical assay showed that the maximum load in three-point bending test of each group increased gradually with time ( P<0.05), and the maximum loads of groups A and D were significantly higher than that of groups B and C at each time point after operation ( P<0.05), but there was no significant difference between groups A and D ( P>0.05). According to the above tests, the optimal mixing ratio was 75% autogenous bone+25% rhBMP-2/PCPC. The process of new bone formation in the experimental group and the control group was observed by gross observation, imaging examination, and histological observation, and the ability of bone formation in the experimental group was better than that in the control group. The ALP activity and maximum load increased gradually with time in both groups ( P<0.05); the ALP activity and maximum load in the experimental group were significantly higher than those in the control group at each time point after operation ( P<0.05), and the maximum load in the experimental group was also significantly higher than that in group A at 12 weeks after operation ( P<0.05).

Conclusion

In the second phase of Masquelet technique, rhBMP-2/PCPC mixed with autologous bone to fill the bone defect can treat large bone defect of rabbit ulna, and it has the best osteogenic ability when the mixing ratio is 75% autologous bone+25% rhBMP-2/PCPC. The combination of PRP can improve the osteogenic ability of rhBMP-2/PCPC and autologous bone mixture.

Clinical Effectiveness of Platelet-Rich Plasma for Long-Bone Delayed Union and Nonunion: A Systematic Review and Meta-Analysis

Background

More recently, there was a series of clinical studies focusing on local administration of platelet-rich plasma (PRP) in long-bone fracture patients suffering from delayed union and nonunion. Therefore, we performed a systematic review to evaluate the effectiveness of PRP injection for treatment of patients with long-bone delayed union and nonunion.

Methods

Relevant clinical trials were selected by the main bibliographic databases, including Medline, PubMed, Embase, Web of Science, and the Cochrane library, to evaluate the effectiveness of PRP for long-bone fracture patients diagnosed with delayed union or nonunion by two reviewers independently. The main outcomes included healing rate, healing duration, pain relief, functional outcome, and complications.

Results

Finally, thirteen studies including four hundred and fifty-nine participants met the selection criteria and were included in this systematic review. These articles included three randomized controlled studies, one prospective study, and nine retrospective studies. 146 out of 155 (94.19%) patients treated with PRP during operation, and 144 out of 183 (78.69%) patients treated with PRP injection alone, exhibited bone consolidation. The healing rate of the PRP group (85.80%) was higher than that of the control group (60.76%). The mean bony union time of patients treated and untreated with PRP, were, respectively, 4.64 and 5.15 months. Four papers reported that PRP was effective in pain relief of patient with delayed union and nonunion. Complications, including small subcutaneous hematoma, subcutaneous swelling, and postoperative infection, were also reported in enrolled studies.

Conclusions

PRP is a promising alternative treatment for patients with long-bone delayed union and nonunion. PRP could successfully promote the healing rate and relieve the pain of patients with delayed union and nonunion. However, the long-term adverse side and functional outcome in application of PRP still need further large-scale trials and long-term follow-up.

Systematic Review Registration

https://www.researchregistry.com/browse-the-registry#home/registrationdetails/61dbd2f837e948001e68d5c5/, The identifying number is research registry 7525.

The role of Platelet Rich Plasma and other orthobiologics in bone healing and fracture management: A systematic review

BACKGROUND

Treatment of large bone defects and fracture healing complications (delayed and non-union) presents a substantial challenge for orthopaedic surgeons. Given that bone healing requires mechanical stability as well as a favourable biological microenvironment, orthobiologics such as Platelet-Rich Plasma (PRP) may have a significant clinical role to play.

AIMS

To perform a systematic review of the available literature to assess the clinical effect of PRP, with or without other orthobiologics, on bone healing.

METHOD

Two independent reviewers performed the literature search based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Clinical studies of any evidence, assessing effect of PRP with or without other orthobiologics on bone healing, were included. A qualitative analysis was carried out on the clinical and radiological outcomes reported.

RESULT

27 articles with 1631 patients (mean age = 43.56, 57.1% male, mean follow-up = 17.27 months) were included in the qualitative. Of the 27 studies, 13 dealt with fracture complications (delayed or non-unions), 7 with acute fracture healing, 4 with tibial osteotomies and lengthening procedures and 3 with lumbar spine pathology. 18/27 studies showed a clinical benefit of PRP, 8/27 showed no significant effect, and 1/27 showed a worse outcome with PRP.

CONCLUSION

Our review suggests PRP may play a clinical role in bone healing but further randomised controlled trials (RCTs) using standardised outcomes should be performed to establish its efficacy.

Eggshell Microparticle Reinforced Scaffolds for Regeneration of Critical Sized Cranial Defects

Scaffold-based approaches for bone regeneration have been studied using a wide range of biomaterials as reinforcing agents to improve the mechanical strength and bioactivity of the 3D constructs. Eggshells are sustainable and inexpensive materials with unique biological and chemical properties to support bone differentiation. The incorporation of eggshell particles within hydrogels yields highly osteoinductive and osteoconductive scaffolds. This study reveals the effects of microparticles of whole eggshells, eggshells without a membrane, and a pristine eggshell membrane on osteogenic differentiation in protein-derived hydrogels. The in vitro studies showed that gels reinforced with eggshells with and without a membrane demonstrated comparable cellular proliferation, osteogenic gene expression, and osteogenic differentiation. Subsequently, in vivo studies were performed to implant eggshell microparticle-reinforced composite hydrogel scaffolds into critical-sized cranial defects in Sprague Dawley (SD) rats for up to 12 weeks to study bone regeneration. The in vivo results showed that the eggshell microparticle-based scaffolds supported an average bone volume of 60 mm³ and a bone density of 2000 HU 12 weeks post implantation. Furthermore, histological analyses of the explanted scaffolds showed that the eggshell microparticle-reinforced scaffolds permitted tissue infiltration and induced bone tissue formation over 12 weeks. The histology staining also indicated that these scaffolds induced significantly higher bone regeneration at 6 and 12 weeks as compared to the blank (no scaffold) and pristine gel scaffolds. The eggshell microparticle-reinforced scaffolds also supported significantly higher bone formation, remodeling, and vascularization over 6 and 12 weeks as confirmed by immunohistochemistry analysis. Collectively, our results indicated that eggshell microparticle-reinforced scaffolds facilitated significant bone regeneration in critical-sized cranial defects.

Using Platelet-Rich Plasma Hydrogel to Deliver Mesenchymal Stem Cells into Three-Dimensional PLGA Scaffold for Cartilage Tissue Engineering

The synthetic biodegradable polyester-based rigid porous scaffolds and cell-laden hydrogels have been separately employed as therapeutic modality for cartilage repair. However, the synthetic rigid scaffolds alone may be limited due to the inherent lack of bioactivity for cartilage regeneration, while the hydrogels have insufficient mechanical properties that are not ideal for load-bearing cartilage applications. In the present study, a hybrid construct was designed to merge the advantage of 3D-printed rigid poly(lactic-co-glycolic acid) (PLGA) scaffolds with cell-laden platelet-rich plasma (PRP) hydrogels that can release growth factors to regulate the tissue healing process. PRP hydrogels potentially achieved the effective delivery of mesenchymal stem cells (MSCs) into PLGA scaffolds. This hybrid construct could obtain adequate mechanical properties and independently provide MSCs with appropriate clues for proliferation and differentiation. Real-time gene expression analysis showed that PRP stimulated both chondrogenic and osteogenic differentiation of MSC seeding into PLGA scaffolds. Finally, the hybrid constructs were implanted into rabbits to simultaneously regenerate both articular cartilage and subchondral bone within osteochondral defects. Our findings suggest that this unique hybrid system could be practically applied for osteochondral regeneration due to its capacity for cell transportation, growth factors release, and excellent mechanical strength, which would greatly contribute to the progress of cartilage tissue engineering.

3D-printed, bioactive ceramic scaffold with rhBMP-2 in treating critical femoral bone defects in rabbits using the induced membrane technique

Although autogenous bone grafts are an optimal filling material for the induced membrane technique, limited availability and complications at the harvest site have created a need for alternative graft materials. We aimed to investigate the effect of an rhBMP-2-coated, 3D-printed, macro/microporous CaO-SiO2 -P2 O5 -B2 O3 bioactive ceramic scaffold in the treatment of critical femoral bone defects in rabbits using the induced membrane technique. A 15-mm segmental bone defect was made in the metadiaphyseal area of the distal femur of 14 rabbits. The defect was filled with polymethylmethacrylate cement and stabilized with a 2.0 mm locking plate. After the membrane matured for 4 weeks, the scaffold was implanted in two randomized groups: Group A (3D-printed bioceramic scaffold) and Group B (3D-printed, bioceramic scaffold with rhBMP-2). Eight weeks after implantation, the radiographic assessment showed that the healing rate of the defect was significantly higher in Group B (7/7, 100%) than in Group A (2/7, 29%). The mean volume of new bone formation around and inside the scaffold doubled in Group B compared to that in Group A. The mean static and dynamic stiffness were significantly higher in Group B. Histological examination revealed newly formed bone in both groups. Extensive cortical bone formation along the scaffold was found in Group B. Successful bone reconstruction in critical-sized bone defects could be obtained using rhBMP-2-coated, 3D-printed, macro/microporous bioactive ceramic scaffolds. This grafting material demonstrated potential as an alternative graft material in the induced membrane technique for reconstructing critical-sized bone defects.

Platelet-rich plasma-derived extracellular vesicles: A superior alternative in regenerative medicine?

Platelet-rich plasma (PRP), due to its promising therapeutic properties, has been used in regenerative medicine for more than 30 years and numerous encouraging outcomes have been obtained. Currently, by benefiting from new insights into PRP mechanisms and the excellent performance of extracellular vesicles (EVs) in the field of tissue repair and regeneration, studies have found that a large number of EVs released from activated platelets also participate in the regulation of tissue repair. A growing number of preclinical studies are exploring the functions of PRP-derived EVs (PRP-EVs), especially in tissue regeneration. Here, we summarize the latest progress in PRP-EVs as a superior alternative cell-free therapeutic strategy in regenerative medicine, clarify their underlying molecular mechanisms, and discuss the advantages and limitations of the upcoming clinical applications. This review highlights the potential of PRP-EVs to replace the application of PRP or even become a superior alternative in regenerative medicine.

Preparation and Characterization of Sustained-Release Naringin Coating on Magnesium Surface

Given the three-dimensional multi-level structure of natural bone and the multi-factor time-shifting effect in the healing process after bone trauma, there are plans to introduce drug-controlled release systems into the treatment of orthopedic diseases. To achieve multi-level loading and controlled release of biologically active substances, it is necessary to create synergistic behavior between biological factors, thereby improving the bone regeneration ability of artificial bone replacement materials. A naringin-loaded (NG) coating was prepared, compared with ultrasonic micro-arc oxidation (UMAO). The coating was characterized by X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. The corrosion resistance of the coating was studied through the wetting angle and polarization curve. The high-performance liquid chromatography method was used to test the release of the drug. It can be seen from the experimental results that the NG coating has a larger wetting angle and better corrosion resistance. In addition, the NG coating produces more apatite substances and has good biological activity. The NG coatings can stimulate the natural bone regeneration and repair process by releasing drugs during the process, which can effectively promote bone regeneration and repair after implantation in the body.

The effect of LyPRP/collagen composite hydrogel on osteogenic differentiation of rBMSCs

Although platelet-rich plasma (PRP) plays a significant role in the orthopedic clinical application, it still faces two major problems, namely, uncontrollable factors release, frequent preparation and extraction processes as well as the inconvenient form of usage. To overcome these shortcomings, freeze-dried PRP (LyPRP) was encapsulated into bioactive Col I hydrogel to induce osteogenic differentiation of rabbit bone marrow mesenchymal stem cells (rBMSCs). And PRP/Col І composite hydrogel was prepared as a control. Compared with Col І hydrogel, the introduction of platelets significantly improved the mechanical properties of hydrogels. Meanwhile, platelets were evenly distributed in the composite hydrogels network. The sustainable release of related factors in the composite hydrogels could last for more than 14 days to maintain its long-term biological activity. Further cell experiments confirmed that PRP and LyPRP could effectively alleviate the contraction of collagen hydrogel in vitro, and promote the adhesion, proliferation and osteogenesis differentiation of rBMSCs. The results of osteogenic gene expression indicated that the 10% LyPRP/Col І composite hydrogel could facilitate the early expression of BMP-2 and late osteogenic associated protein formation with higher expression of alkaline phosphatase and Osteocalcin (OCN). These results might provide new insights for the clinical application of 10% LyPRP/Col І composite hydrogel as practical bone repair injection.

Platelet-Rich Plasma Therapy in the Treatment of Diseases Associated with Orthopedic Injuries

Platelet-rich plasma (PRP) is an autologous platelet concentrate prepared from the whole blood that is activated to release growth factors (GFs) and cytokines and has been shown to have the potential capacity to reduce inflammation and improve tissue anabolism for regeneration. The use of PRP provides a potential for repair due to its abundant GFs and cytokines, which are key in initiating and modulating regenerative microenvironments for soft and hard tissues. Among outpatients, orthopedic injuries are common and include bone defects, ligament injury, enthesopathy, musculoskeletal injury, peripheral nerve injury, chronic nonhealing wounds, articular cartilage lesions, and osteoarthritis, which are caused by trauma, sport-related or other types of trauma, or tumor resection. Surgical intervention is often required to treat these injuries. However, for numerous reasons regarding limited regeneration capacity and insufficient blood supply of the defect region, these treatments commonly result in unsatisfactory outcomes, and follow-up treatment is challenging. The aim of the present review is to explore future research in the field of PRP therapy in the treatment of diseases associated with orthopedic injuries. Impact statement In recent years, platelet-rich plasma (PRP) has become widely used in the treatment of diseases associated with orthopedic injuries, and the results of numerous studies are encouraging. Due to diseases associated with orthopedic injuries being common in clinics, as a conservative treatment, more and more doctors and patients are more likely to accept PRP. Importantly, PRP is a biological product of autologous blood that is obtained by a centrifugation procedure to enrich platelets from whole blood, resulting in few complications, such as negligible immunogenicity from an autologous source, and it is also simple to produce through an efficient and cost-effective method in a sterile environment. However, the applicability, advantages, and disadvantages of PRP therapy have not yet been fully elucidated. The aim of the present review is to explore future research in the field of PRP therapy in the treatment of diseases associated with orthopedic injuries, as well as to provide references for clinics.

Vascularization Strategies in the Prevention of Nonunion Formation

Delayed healing and nonunion formation are major challenges in orthopedic surgery, which require the development of novel treatment strategies. Vascularization is considered one of the major prerequisites for successful bone healing, providing an adequate nutrient supply and allowing the infiltration of progenitor cells to the fracture site. Hence, during the last decade, a considerable number of studies have focused on the evaluation of vascularization strategies to prevent or to treat nonunion formation. These involve (1) biophysical applications, (2) systemic pharmacological interventions, and (3) tissue engineering, including sophisticated scaffold materials, local growth factor delivery systems, cell-based techniques, and surgical vascularization approaches. Accumulating evidence indicates that in nonunions, these strategies are indeed capable of improving the process of bone healing. The major challenge for the future will now be the translation of these strategies into clinical practice to make them accessible for the majority of patients. If this succeeds, these vascularization strategies may markedly reduce the incidence of nonunion formation. Impact statement Delayed healing and nonunion formation are a major clinical problem in orthopedic surgery. This review provides an overview of vascularization strategies for the prevention and treatment of nonunions. The successful translation of these strategies in clinical practice is of major importance to achieve adequate bone healing.

Repair of rat cranial bone defect by using amniotic fluid-derived mesenchymal stem cells in polycaprolactone fibrous scaffolds and platelet-rich plasma

Introduction: Tissue regenerative medicine strategies, as a promising alternative has become of major interest to the reconstruction of critical size bone defects. This study evaluated the effects of the simultaneous application of polycaprolactone (PCL), amniotic fluid mesenchymal stem cells (AF-MSCs) and platelet-rich plasma (PRP) on the repair of rat cranial bone defects. Methods: The AF-MSCs were isolated at the end of the second week of pregnancy in rats. PRP obtained from rat blood and the random PCL fibrous scaffolds were prepared using the electrospinning method. Circular full thickness (5 mm) bone defects were developed on both sides of the parietal bones (animal number=24) and the scaffolds containing AF-MSCs and PRP were implanted in the right lesions. Thereafter, after eight weeks the histological and immunohistochemistry studies were performed to evaluate the bone formation and collagen type I expression. Results: The spindle-shaped mesenchymal stem cells were isolated and the electron microscope images indicated the preparation of a random PCL scaffold. Immunohistochemical findings showed that collagen type I was expressed by AF-MSCs cultured on the scaffold. The results of hematoxylin and eosin (H&E) staining indicated the formation of blood vessels in the presence of PRP. Additionally, immunofluorescence findings suggested that PRP had a positive effect on collagen type I expression. Conclusion: The simultaneous application of fibrous scaffold + AF-MSCs + PRP has positive effects on bone regeneration. This study showed that PRP can affect the formation of new blood vessels in the scaffold transplanted in the bone defect.

Integrating silicon/zinc dual elements with PLGA microspheres in calcium phosphate cement scaffolds synergistically enhances bone regeneration

Integrating multiple pro-osteogenic factors into bone graft substitutes is a practical and effective approach to improve bone repair efficacy. Here, Si-Zn dual elements and PLGA microspheres were incorporated into calcium phosphate cement (CPC) scaffolds (PLGA/CPC-Si/Zn) as a novel strategy to synergistically enhance bone regeneration. The incorporation of PLGA microspheres and Si/Zn dual elements within CPC scaffolds improved the setting time, injectability and compressive strength. The PLGA/CPC-Si/Zn scaffolds displayed controlled sequential release of Si and Zn ions. In vitro, RAW 264.7 cells displayed the M2 phenotype with a high level of anti-inflammatory cytokines in response to PLGA/CPC-Si/Zn. The conditioned medium of RAW 264.7 cells cultured on the PLGA/CPC-Si/Zn scaffolds significantly enhanced the osteogenic differentiation of rat BMSCs. In a rat femur defect model, the implanted PLGA/CPC-Si/Zn scaffolds led to obvious new bone formation after 4 weeks, apparent bone ingrowth into the PLGA microspheres after 12 weeks, and was almost completely filled with mature new bone upon degradation of the PLGA microspheres at 24 weeks. These findings demonstrate that the PLGA/CPC-Si/Zn scaffolds promote osteogenesis by synergistically improving the immune microenvironment and biodegradability. Hence, integrating multiple trace elements together with degradable components within bone graft biomaterials can be an effective strategy for promoting bone regeneration.

Augmented osteogenesis of mesenchymal stem cells using a fragmented Runx2 mixed with cell-penetrating, dimeric a-helical peptide

The intracellular delivery of transcription factor/cofactor using cell penetrating peptide (CPP) can lead to selective osteogenesis. The present work investigates the cell-penetrating potential of the a cyclic, α-helical cell-penetrating peptide based on leucine and lysine residues (cLK) for intracellular delivery in MC3T3 cells and the osteogenic effects of a C-terminal proline‑serine‑threonine-rich (PST) domain of Runx2 using cLK in rat mesenchymal stem cells (MSCs). We confirmed that the combination of cLK and fluorescein 5-isothiocyanate (FITC)-fragmented-Runx2 (fRunx2) showed an enhanced cell-penetrating activity of FITC-fRunx2 compared with FITC-fRunx2 alone. In addition, the fRunx2-cLK group showed strong staining with alizarin red compared with other groups and the degree of alizarin red staining in the fRunx2-cLK group was also 1.2-fold higher than that in the fRunx2-Tat group. The ALP and osteocalcin gene expression levels in the fRunx2-cLK group were higher than those in the other groups. The fRunx2 transferred effectively into the cytoplasm aided by the cLK peptide and augmented the osteogenic differentiation of MSCs.

PRP and BMAC for Musculoskeletal Conditions via Biomaterial Carriers

Platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC) are orthobiologic therapies considered as an alternative to the current therapies for muscle, bone and cartilage. Different formulations of biomaterials have been used as carriers for PRP and BMAC in order to increase regenerative processes. The most common biomaterials utilized in conjunction with PRP and BMAC clinical trials are organic scaffolds and natural or synthetic polymers. This review will cover the combinatorial strategies of biomaterial carriers with PRP and BMAC for musculoskeletal conditions (MsCs) repair and regeneration in clinical trials. The main objective is to review the therapeutic use of PRP and BMAC as a treatment option for muscle, bone and cartilage injuries.

[Effect of icariin/attapulgite/collagen type /polycaprolactone composite scaffold in repair of rabbit tibia defect]

OBJECTIVE

To investigate the effect of icarin/attapulgite/collagen type Ⅰ/polycaprolactone (ICA/ATP/Col Ⅰ/PCL) composite scaffold in repair of rabbit tibia defect.

METHODS

The ICA/20%ATP/Col Ⅰ/PCL (scaffold 1), ICA/30%ATP/Col Ⅰ/PCL (scaffold 2), 20%ATP/Col Ⅰ/PCL (scaffold 3), and 30%ATP/Col Ⅰ/PCL (scaffold 4) composite scaffolds were constructed by solution casting-particle filtration method. The structure characteristics of the scaffold 2 before and after cross-linking were observed by scanning electron microscopy, and the surface contact angles of the scaffold 2 and the scaffold 4 were used to evaluate the water absorption performance of the material. The in vitro degradation test was used to evaluate the sustained-release effect of the scaffold 2. Thirty male Japanese white rabbits, weighing (2.0±0.1) kg, were randomly divided into groups A, B, C, D, and E, 6 in each group. After making a 1 cm- diameter bilateral tibial defects model, group A was the defect control group without any material implanted. Groups B, C, D, and E were implanted with scaffolds 3, 4, 1, and 2 at the defect sites, respectively. At 4, 8, and 12 weeks after operation, the repairing effects of 4 scaffolds were observed by gross observation, histological observation of HE and Masson staining, and immunohistochemical staining of osteogenic specific transcription factor (runt-related transcription factor 2, RUNX2), osteogenic related transcription factor [Osterix (OSX), Col Ⅰ, osteopontin (OPN)].

RESULTS

Scanning electron microscopy observation showed that the scaffolds were all porous. The structure of the material was loose before and after cross-linking. The surface contact angle showed that the scaffold was hydrophobic, and the scaffold 2 was more hydrophobic than scaffold 4. The sustained-release effect in vitro showed that the drug could be released in a micro and long-term manner. In the animal implantation experiment, the gross observation showed that the defects were significantly smaller in groups D and E than in groups A, B, and C at 4 and 12 weeks after operation. HE and Masson staining showed that the defect of group A was full of connective tissue at 4 weeks after operation, a large number of fibers were seen in groups B and C, and the new bone formation was observed in groups D and E. The increase of new bone was observed in each group at 8 weeks after operation. The defect of group A was still dominated by connective tissue at 12 weeks after operation, and a small amount of new bone tissue was observed in groups B and C, and a large number of new bone tissue was observed in groups D and E, especially in group E, and most of the materials degraded. Immunohistochemical staining showed that the expressions of RUNX2 and OSX in the new tissues of groups D and E were significantly higher than those of the other groups at 4 weeks after operation. The expression of RUNX2 decreased at 8 and 12 weeks after operation. After 8 weeks and 12 weeks, the expressions of Col Ⅰand OPN increased than in 4 weeks. And the expressions of Col Ⅰ and OPN in the new tissues of groups D and E were significantly more than those of the other groups.

CONCLUSION

ICA/ATP/Col I/PCL composite scaffolds have good porosity and biocompatibility, can promote bone formation, and have good bone regeneration and repair effect.

Fabrication and properties of an injectable sodium alginate/PRP composite hydrogel as a potential cell carrier for cartilage repair

Three-dimensional scaffolds like hydrogels can be employed as cell carriers for in vitro or in vivo colonization and have become a major research topic to replace damaged tissue. In the current study, a novel composite hydrogel composed of sodium alginate (SA) and platelet-rich-plasma (PRP) varying in blending ratios, cross-linked with calcium ions, released from calcium carbonate-D-Glucono-d-lactone (CaCO₃ -GDL) was successfully prepared. It was found that addition of PRP changed largely the physical properties and biological performance of the composite hydrogels, which was depending on the blending ratio. The gelation rate and swelling ratio of alginate hydrogels were significantly reduced by the addition of PRP, which produced also a more homogeneous gel structure. Field emission scanning electron microscopy (FE-SEM) investigation confirmed the incorporation of PRP-derived proteins in the hydrogel, where a porous structure with a pore size of 200-300 μm was found. On the other hand, an increase in surface roughness was observed after the addition of PRP. The compressive mechanical strength of SA/PRP composite hydrogel was enhanced in comparison to the pure SA gel. The composite hydrogels with the highest PRP content exhibited at a maximum compressive stress of 0.26 MPa a maximum strain of 55%, while the maximum compressive strain of pure SA hydrogels was only 45% at a stress of 0.08 MPa. It was also found that the in vitro degradation of the alginate gel was accelerated by the addition of PRP. In terms of cellular responses, all gels exhibited an excellent cytocompatibility. Indeed, the composite hydrogels supported bone marrow-derived mesenchymal stem cells proliferation and their chondrogenesis with up-regulation of chondrogenic marker genes Sox9 and Aggrecan. Overall, the present study suggests a great potential of SA/PRP composite hydrogels as cell carriers for cartilage tissue engineering.

Argon plasma surface modification promotes the therapeutic angiogenesis and tissue formation of tissue-engineered scaffolds in vivo by adipose-derived stem cells

Background

Synthetic implants are being used to restore injured or damaged tissues following cancer resection and congenital diseases. However, the survival of large tissue implant replacements depends on their ability to support angiogenesis that if limited, causes extrusion and infection of the implant. This study assessed the beneficial effect of platelet-rich plasma (PRP) and adipose-derived stem cells (ADSCs) on synthetic biomaterials in combination with argon plasma surface modification to enhance vascularisation of tissue-engineered constructs.

Methods

Non-biodegradable polyurethane scaffolds were manufactured and modified with plasma surface modification using argon gas (PM). Donor rats were then used to extract ADSCs and PRP to modify the scaffolds further. Scaffolds with and without PM were modified with and without ADSCs and PRP and subcutaneously implanted in the dorsum of rats for 3 months. After 12 weeks, the scaffolds were excised and the degree of tissue integration using H&E staining and Masson’s trichrome staining, angiogenesis by CD31 and immune response by CD45 and CD68 immunohistochemistry staining was examined.

Results

H&E and Masson’s trichrome staining showed PM+PRP+ADSC and PM+ADSC scaffolds had the greatest tissue integration, but there was no significant difference between the two scaffolds (p < 0.05). The greatest vessel formation after 3 months was shown with PM+PRP+ADSC and PM+ADSC scaffolds using CD31 staining compared to all other scaffolds (p < 0.05). The CD45 and CD68 staining was similar between all scaffolds after 3 months showing the ADSCs or PRP had no effect on the immune response of the scaffolds.

Conclusions

Argon plasma surface modification enhanced the effect of adipose-derived stem cells effect on angiogenesis and tissue integration of polyurethane scaffolds. The combination of ADSCs and argon plasma modification may improve the survival of large tissue implants for regenerative applications.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1195-z) contains supplementary material, which is available to authorized users.

Calcium Phosphate Spacers for the Local Delivery of Sitafloxacin and Rifampin to Treat Orthopedic Infections: Efficacy and Proof of Concept in a Mouse Model of Single-Stage Revision of Device-Associated Osteomyelitis

Osteomyelitis is a chronic bone infection that is often treated with adjuvant antibiotic-impregnated poly(methyl methacrylate) (PMMA) cement spacers in multi-staged revisions. However, failure rates remain substantial due to recurrence of infection, which is attributed to the poor performance of the PMMA cement as a drug release device. Hence, the objective of this study was to design and evaluate a bioresorbable calcium phosphate scaffold (CaPS) for sustained antimicrobial drug release and investigate its efficacy in a murine model of femoral implant-associated osteomyelitis. Incorporating rifampin and sitafloxacin, which are effective against bacterial phenotypes responsible for bacterial persistence, into 3D-printed CaPS coated with poly(lactic co-glycolic) acid, achieved controlled release for up to two weeks. Implantation into the murine infection model resulted in decreased bacterial colonization rates at 3- and 10-weeks post-revision for the 3D printed CaPS in comparison to gentamicin-laden PMMA. Furthermore, a significant increase in bone formation was observed for 3D printed CaPS incorporated with rifampin at 3 and 10 weeks. The results of this study demonstrate that osteoconductive 3D printed CaPS incorporated with antimicrobials demonstrate more efficacious bacterial colonization outcomes and bone growth in a single-stage revision in comparison to gentamicin-laden PMMA requiring a two-stage revision.

Chitosan/biphasic calcium phosphate scaffolds functionalized with BMP-2-encapsulated nanoparticles and RGD for bone regeneration

Advancements in bone tissue engineering require the improvement of tissue scaffolds, which should not only exhibit suitable mechanical properties and highly porous structures, but also effectively carry signaling molecules that can mediate bone formation and tissue regeneration. In the present study, we established chitosan/biphasic calcium phosphate (CS/BCP) scaffolds functionalized with Arg-Gly-Asp (RGD) and BMP-2-loaded nanoparticles. The resulting scaffolds were highly similar to natural bone extracellular matrix (ECM) in terms of composition and structural properties. First, we synthesized CS/BCP composite bionic scaffolds via the freeze-drying method. Then, RGD peptides were covalently conjugated onto the scaffolds via the EDC/NHS method. The BMP-2-encapsulated BSA nanoparticles were prepared via a desolvation method and then coated with CS and oxidized alginate to achieve sustained release of BMP-2. In vitro cell culture and in vivo implantation tests confirmed that RGD and BMP-2 synergistically enhanced cell attachment and spreading by providing integrin binding surface and facilitating osteogenic differentiation. In summary, the bioceramic/biopolymer scaffolds functionalized with signaling biomolecules successfully provided a favorable microenvironment for bone formation and thus serve as potential candidates for use in bone tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2613-2624, 2018.

Bone Regeneration of Osteoporotic Vertebral Body Defects Using Platelet-Rich Plasma and Gelatin β-Tricalcium Phosphate Sponges

The objective of the present study was to investigate the effect of platelet-rich plasma (PRP) combined with gelatin β-tricalcium phosphate (β-TCP) sponge on bone generation in a lumbar vertebral body defect of ovariectomized rat. After creating critical-size defects in the center of the anterior vertebral body, the defects were filled with the following materials: (1) no material (control group), (2) gelatin β-TCP sponge with PRP (PRP sponge group), and (3) gelatin β-TCP sponge with phosphate-buffered saline (PBS sponge group). Microcomputed tomography and histological evaluation were performed immediately after surgery and at 4, 8, and 12 weeks to assess bone regeneration. Biomechanical test was also performed at postoperative week 12. In the PRP sponge group, both imaging and histological examination showed that visible osteogenesis was first induced and additional growth of bone tissue was observed in the transplanted sponge, compared with the PBS sponge group. There was no negative effect of either PRP sponge or PBS sponge transplantation on bone tissue generation around the periphery of the defect. Biomechanical test showed increased stiffness of the affected vertebral bodies in the PRP sponge group. These results indicate that PRP-impregnated gelatin β-TCP sponge is effective for facilitating bone regeneration in lumbar vertebral bone defect under osteoporotic condition. PRP combined with gelatin β-TCP sponges could be potentially useful for developing a new approach to vertebroplasty for osteoporotic vertebral fracture.

Healing potentials of polymethylmethacrylate bone cement combined with platelet gel in the critical-sized radial bone defect of rats

Polymethylmethacrylate (PMMA) is the most commonly used filler material that lacks biological properties and osteoconductivity or osteoinductivity. Platelet gel (PG) is a typical source of growth factors, cytokines and molecules efficient for bone formation and remodeling. The aim of this study was to evaluate bone healing and regeneration of bone defect in rat model by combining PMMA with PG. A total of 50 defects were created in the diaphysis of the radii of 25 male Sprague-Dawley rats. These defects were randomly divided into five groups (n = 10 defects for each group) and treated by autograft, plain PMMA, PG and PMMA-PG or left untreated. The rats were examined clinically and radiologically during the experiment and also after euthanasia at the 8^th post-operative week, the healed defects were evaluated by gross morphology, histopathology, histomorphometry, computed tomography, scanning electron microscopy and biomechanical testing. PG could function as efficiently as autograft in promoting bone healing of the radial bones. Additionally, bone formation, and densities of cartilaginous and osseous tissues in the defects treated with autograft, PG and PMMA-PG were more satisfactory than the untreated and PMMA treated defects. Compared with the PMMA-PG implant, more PMMA residuals remained in the defect area and induced more intense inflammatory reaction. In conclusion, addition of PG could improve the bone regenerative properties of PMMA bone cement compared with PMMA alone in vivo. Therefore, the PG-PMMA can be proposed as a promising option to increase regenerative potential of PMMA, particularly when it is used as fixator, filler or adhesive in the dentistry, neurosurgery and bone tissue engineering applications.

New approach in evaluation of ceramic-polymer composite bioactivity and biocompatibility

Regeneration of bone defects was promoted by a novel β-glucan/carbonate hydroxyapatite composite and characterized by Raman spectroscopy, microCT and electron microscopy. The elastic biomaterial with an apatite-forming ability was developed for bone tissue engineering and implanted into the critical-size defects of rabbits' tibiae. The bone repair process was analyzed on non-decalcified bone/implant sections during a 6-month regeneration period. Using spectroscopic methods, we were able to determine the presence of amides, lipids and assign the areas of newly formed bone tissue. Raman spectroscopy was also used to assess the chemical changes in the composite before and after the implantation process. SEM analyses showed the mineralization degree in the defect area and that the gap size decreased significantly. Microscopic images revealed that the implant debris were interconnected to the poorly mineralized inner side of a new bone tissue. Our study demonstrated that the composite may serve as a biocompatible background for collagen ingrowth and exhibits the advantages of applying Raman spectroscopy, SEM and microCT in studying these samples.

An Innovative Approach for Enhancing Bone Defect Healing Using PLGA Scaffolds Seeded with Extracorporeal-shock-wave-treated Bone Marrow Mesenchymal Stem Cells (BMSCs)

Although great efforts are being made using growth factors and gene therapy, the repair of bone defects remains a major challenge in modern medicine that has resulted in an increased burden on both healthcare and the economy. Emerging tissue engineering techniques that use of combination of biodegradable poly-lactic-co-glycolic acid (PLGA) and mesenchymal stem cells have shed light on improving bone defect healing; however, additional growth factors are also required with these methods. Therefore, the development of novel and cost-effective approaches is of great importance. Our in vitro results demonstrated that ESW treatment (10 kV, 500 pulses) has a stimulatory effect on the proliferation and osteogenic differentiation of bone marrow-derived MSCs (BMSCs). Histological and micro-CT results showed that PLGA scaffolds seeded with ESW-treated BMSCs produced more bone-like tissue with commitment to the osteogenic lineage when subcutaneously implanted in vivo, as compared to control group. Significantly greater bone formation with a faster mineral apposition rate inside the defect site was observed in the ESW group compared to control group. Biomechanical parameters, including ultimate load and stress at failure, improved over time and were superior to those of the control group. Taken together, this innovative approach shows significant potential in bone tissue regeneration.

Application of selected scaffolds for bone tissue engineering: a systematic review

PURPOSE

The current systematic review investigated the results of application of some of the most commonly used scaffolds in conjugation with stem cells and growth factors in animal and clinical studies.

METHODS

A comprehensive electronic search was conducted according to the PRISMA guidelines in NCBI PMC and PubMed from January 1970 to December 2015 limited to English language publications with available full texts. In vivo studies in relation to "bone healing," "bone regeneration," and at least one of the following items were investigated: allograft, β-tricalcium phosphate, deproteinized bovine bone mineral, hydroxyapetite/tricalcium phosphate, nanohydroxyapatite, and composite scaffolds.

RESULTS

A total of 1252 articles were reviewed, and 46 articles completely fulfilled the inclusion criteria of this study. The highest bone regeneration has been achieved when combination of all three elements, given scaffolds, mesenchymal stem cells, and growth factors, were used. Among studies being reported in this review, bone marrow mesenchymal stem cells are the most studied mesenchymal stem cells, β-tricalcium phosphate is the most frequently used scaffold, and platelet-rich plasma is the most commonly used growth factor.

CONCLUSION

The current review aimed to inform reconstructive surgeons of how combinations of various mesenchymal stem cells, scaffolds, and growth factors enhance bone regeneration. The highest bone regeneration has been achieved when combination of all three elements, given scaffolds, mesenchymal stem cells, and growth factors, were used.

Platelet-rich plasma for the treatment of bone defects: from pre-clinical rational to evidence in the clinical practice. A systematic review

PURPOSE

The treatment of large bone defects represents a significant challenge for orthopaedic surgeons. In recent years, biologic agents have also been used to further improve bone healing. Among these, platelet-rich plasma (PRP) is the most exploited strategy. The aim of the present study was to systematically review the available literature to identify: 1) preclinical in-vivo results supporting the rational of PRP use for bone healing; 2) evidence from the clinical practice on the actual clinical benefit of PRP for the treatment of fractures and complications such as delayed unions and non-unions.

METHODS

A systematic review of the literature was performed on the application of PRP in bone healing, using the following inclusion criteria: pre-clinical and clinical reports of any level of evidence, written in English language, published in the last 20 years (1996-2016), on the use of PRP to stimulate long-bone defect treatment, with focus on fracture and delayed/non-unions healing.

RESULTS

The search in the Pubmed database identified 64 articles eligible for inclusion: 45 were preclinical in-vivo studies and 19 were clinical studies. Despite the fact that the overall pre-clinical results seem to support the benefit of PRP in 91.1 % of the studies, a more in depth analysis underlined a lower success rate, with a positive outcome of 84.4 % in terms of histological analysis, and even lower values considering radiological and biomechanical results (75.0 % and 72.7 % positive outcome respectively). This was also mirrored in the clinical literature, where the real benefit of PRP use to treat fractures and non-unions is still under debate.

CONCLUSION

Overall, the available literature presents major limitations in terms of low quality and extreme heterogeneity, which hamper the possibility to optimize PRP treatment and translate it into a real clinical benefit despite positive preclinical findings on its biological potential to favour bone healing.

Combined treatment with platelet-rich plasma and insulin favours chondrogenic and osteogenic differentiation of human adipose-derived stem cells in three-dimensional collagen scaffolds

Osteochondral lesions due to injury or other pathology commonly result in the development of osteoarthritis and progressive joint destruction. Bioengineered scaffolds are widely studied for regenerative surgery strategies in osteochondral defect management, also combining the use of stem cells, growth factors and hormones. The utility in tissue engineering of human adipose-derived stem cells (ASCs) isolated from adipose tissue has been widely noted. Autologous platelet-rich plasma (PRP) represents an alternative strategy in regenerative medicine for the local release of endogenous growth factors and hormones. Here we compared the effects of three-dimensional (3D) collagen type I scaffold culture and combined treatment with PRP and human recombinant insulin on the chondro-/osteogenic differentiation of ASCs. Histochemical and biomolecular analyses demonstrated that chondro-/osteogenic differentiation was increased in ASC-populated 3D collagen scaffolds compared with two-dimensional (2D) plastic dish culture. Chondro-/osteogenic differentiation was further enhanced in the presence of combined PRP (5% v/v) and insulin (100 nm) treatment. In addition, chondro-/osteogenic differentiation associated with the contraction of ASC-populated 3D collagen scaffold and increased β1/β3-integrin expression. Inhibition studies demonstrated that PRP/insulin-induced chondro-/osteogenic differentiation is independent of insulin-like growth factor 1 receptor (IGF-1R) and mammalian target of rapamycin (mTOR) signalling; IGF-R1/mTOR inhibition even enhanced ASC chondro-/osteogenic differentiation. Our findings underline that 3D collagen scaffold culture in association with platelet-derived growth factors and insulin favour the chondro-/osteogenic differentiation of ASCs, suggesting new translational applications in regenerative medicine for the management of osteochondral defects. Copyright © 2016 John Wiley & Sons, Ltd.

Lithium doped calcium phosphate cement maintains physical mechanical properties and promotes osteoblast proliferation and differentiation

Calcium phosphate cement (CPC) has been widely used in bone tissue repairing due to its physical mechanical properties and biocompatibility. Addition of trace element to CPC has shown promising evidence to improve the physical properties and biological activities of CPC. Lithium (Li) has effect on osteoblast proliferation and differentiation. In this study, we incorporated Li to CPC and examined the physical properties of Li/CPC and its effect on osteoblast proliferation and differentiation. We found that Li doped CPC maintained similar setting time, pore size distribution, compressive strength, composition, and morphology as CPC without Li. Additionally, Li doped CPC improved osteoblast proliferation and differentiation significantly compared to CPC without Li. To our knowledge, our results, for the first time, show that Li doped CPC has beneficial effect on osteoblast in cell culture while keeps the excellent physical-mechanical properties of CPC. This study will lead to potential application of Li doped CPC in bone tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 944-952, 2017.

Bone cements for percutaneous vertebroplasty and balloon kyphoplasty: Current status and future developments

Osteoporotic vertebral compression fractures (OVCFs) have gradually evolved into a serious health care problem globally. In order to reduce the morbidity of OVCF patients and improve their life quality, two minimally invasive surgery procedures, vertebroplasty (VP) and balloon kyphoplasty (BKP), have been developed. Both VP and BKP require the injection of bone cement into the vertebrae of patients to stabilize fractured vertebra. As such, bone cement as the filling material plays an essential role in the effectiveness of these treatments. In this review article, we summarize the bone cements that are currently available in the market and those still under development. Two major categories of bone cements, nondegradable acrylic bone cements (ABCs) and degradable calcium phosphate cements (CPCs), are introduced in detail. We also provide our perspectives on the future development of bone cements for VP and BKP.