Platelet-rich plasma stimulates osteoblastic differentiation in the presence of BMPs

The Use of Stromal Vascular Fraction, Platelet-rich Plasma, and Stem Cells in the Treatment of Thumb Carpometacarpal Osteoarthritis

Background

Thumb function is integral to hand movement and overall hand function. Impairment, often caused by carpometacarpal (CMC) arthritis, reduces the quality of life. Here, we explored a novel approach using a mixture of the stromal vascular fraction, adipose-derived stem cells, and platelet-rich plasma to treat symptomatic trapeziometacarpal osteoarthritis.

Methods

Retrospective data from 30 hands of 19 patients classified as Eaton and Littler stages 1-4 were analyzed. Platelet-rich plasma and fat were collected under sterile conditions, followed by centrifugation, stem cell extraction, and injection of the mixture into the thumb CMC joint under x-ray guidance. The measurement parameters included the visual analog scale pain score, grip strength, pinch strength, and Thumb Disability Examination (TDX) score. Statistical analysis was performed using paired t tests to evaluate the outcomes across the entire group, individual stages, and early/late stages.

Results

We examined 30 hands of 19 patients with trapeziometacarpal osteoarthritis. Pain reduction was significant at 6 and 24 months for all stages, particularly stages 2 and 3. Substantial pain reduction was also observed at the early and late stages. The TDX score decreased significantly in all groups after 6 and 24 months. Hand function notably improved with significant gains in tip-to-tip pinch strength at 24 months and palmar pinch strength at 6 and 24 months. No complications were observed.

Conclusions

The intra-articular injection of autologous conditioned plasma/stromal vascular fraction in patients with thumb CMC arthritis, in all stages, helps to improve pain symptoms and postpone potential resection arthroplasty with minimal surgical intervention and risks.

Efficacy of small-diameter core decompression with platelet-rich plasma in early osteonecrosis of the femoral head: a retrospective study

BACKGROUND

Osteonecrosis of the femoral head (ONFH) is a challenging condition, primarily affecting young and middle-aged individuals, which results in hip dysfunction and, ultimately, femoral head collapse. However, the comparative effectiveness of joint-preserving procedures, particularly in the early stages of ONFH (ARCO stage I or II), remains inconclusive. This study aims to evaluate the efficacy of a novel technique called small-diameter core decompression (CD) combined with platelet-rich plasma (PRP), for the treatment of early-stage ONFH.

METHODS

Clinical data of 40 patients (51 hips) with pre-collapse stage ONFH were retrospectively analyzed. Nineteen patients (23 hips) underwent small-diameter CD + PRP (group A) and 21 patients (28 hips) received conventional CD (group B) and follow-up was conducted every 3 months. Hip radiographs (X-rays and MRI) were evaluated using various ONFH staging systems (Preserved Angles, ARCO, JIC, and CHFJ stages). X-rays were performed at each follow-up to assess femoral head collapse and the rate of total hip arthroplasty (THA). Additionally, the Visual Analogue Scale (VAS), Harris Hip Score (HHS), Charnley score, SF-36, Athens Insomnia Scale (AIS), and State-Trait Anxiety Inventory (STAI) were used to evaluate hip pain, function, quality of life, and psychological status. These assessments were conducted both preoperatively and at each follow-up visit.

RESULTS

The mean follow-up duration in Group A was 11.57 months, with a femoral head survivorship of 82.61%. One hip underwent THA 14 months after the novel procedure. In Group B, with an average follow-up period of 11.32 months, femoral head survivorship was 60.71% (p = 0.111), and 2 hips required THA (p = 0.999). At the final follow-up, the VAS, stiffness, HHS and Charnley scores of Group A showed significant improvements compared to those in Group B. Quality of life, anxiety and insomnia were also significantly improved in the Group A compared to Group B.

CONCLUSION

The application of PRP following CD results in significant pain relief, improved short-term functional outcomes, and enhanced quality of life compared to CD alone. However, whether it hinders disease progression in early ONFH and reduces the conversion rate to THA and femoral head collapse remains uncertain. Further research with larger sample sizes and extended follow-up is needed to validate these preliminary findings.

Current Review of Regenerative Medicine Therapies for Spine-Related Pain

PURPOSE OF REVIEW

Persistent spinal pain syndromes are pervasive and lead to functional impairment, increased healthcare utilization, potential disability, and high societal costs. Spinal (cervical, thoracic, lumbar, and sacroiliac joint) pain includes mechanical, degenerative, inflammatory, oncologic, and infectious etiologies. Regenerative medicine is a novel biotechnology targeting mechanical, degenerative, and inflammatory conditions believed to cause pain. Preparations including platelet-rich plasma, mesenchymal stem cells (adipose tissue and bone marrow aspirate concentrates), and growth factors are derived from an autologous donor. The goal of intervention through guided injection of the regenerative media is to reduce inflammation and reverse the degenerative cascade in hopes of restoring normal cellular composition (physiologic homeostasis) and anatomical function to improve pain and function. The authors review limited research supporting the use of platelet-rich plasma injections for facet joint arthropathy and sacroiliac joint pain compared to traditional steroid treatments, as well as the use of platelet rich plasma or mesenchymal stem cells for lumbar discogenic and radicular pain.

RECENT FINDINGS

Current evidence to support regenerative medicine for spine-related pain is limited. Although several studies demonstrated a reduction in pain, many of these studies had a small number of participants and were case series or prospective trials. Regenerative medicine treatments lack evidence for the treatment of spine-related pain. Large randomized controlled trials are needed with consistent study protocols to make further recommendations.

Comparison of the Effect of Platelet-rich Plasma (PRP) and Fat Graft on Autologous Bone Grafting in a Randomized-controlled Experimental Skull Model

Gold standard method for the treatment of critical-sized bone defects is the autogenous bone grafting procedure. A number of new and potentially useful adjuncts currently are being investigated to enhance the success of bone grafting. We propose to evaluate the effect of the most known and easily obtained 2 biological materials, fat graft and platelet-rich plasma (PRP), on bone graft healing. Twenty-seven New Zealand male rabbits were included in this randomized, controlled study. Two-sided 15-mm diameter bone defects were created in the parietal bones and the bones taken were replaced right-to-left and vice versa with 1 control group, 1 fat graft applied group, and the last one PRP applied group. Histologic evaluation and 3-dimensional maxillofacial computerized tomography were performed and bone density was calculated. In radiologic analysis, bone density was significantly different in the PRP group compared with the control and fat graft group in the 12th week ( P <0.05). In histologic scoring analysis, the PRP group had a better score than the control and fat graft group, while the fat graft group was worse than the control group in the 6th week ( P <0.05). The addition of PRP had a positive effect whereas fat graft had a negative effect on bone graft healing compared with the control group.

Advances in the Clinical Application of Platelet-Rich Plasma in the Foot and Ankle: A Review

Autologous and recombinant biologic substances have been generated as a result of the research into the cellular features of the healing process. Orthobiologics are increasingly being used in sports medicine and musculoskeletal surgery. Nevertheless, clinical data are limited; consequently, further studies are required, particularly in foot and ankle pathologies. This review aims to provide evidence of the most recent literature results and ignite the interest of orthopedic specialists eager for an update about the most current discussion on platelet-rich plasma (PRP) clinical applications in the foot and ankle fields. Previous studies have shown that platelet-rich plasma can be beneficial in treating various conditions, such as chronic foot ulcers, osteoarthritis, Achilles tendinopathy, etc. Despite the positive effects of PRP on various musculoskeletal conditions, more prospective studies are needed to confirm its effectiveness at treating ankle and foot pathologies. In addition to clinical trials, other factors, such as the quality of the research and the procedures involved, must be considered before they can be used in patients. More long-term evaluations are needed to support or oppose its application in treating foot and ankle disorders. We present the most extensive review of PRP's clinical applications in the foot and ankle field.

Hormesis mediates platelet-rich plasma and wound healing

Platelet-rich plasma (PRP) has become an accepted and general wound healing approach with an extremely wide range of applications. Despite considerable diversity in the composition of platelet-rich plasma products that are applied in specific wound healing usage, it is widely recognised that such diverse platelet-rich plasma complex mixtures routinely display hormetic-like biphasic concentrations that are independent of the tissue treated and endpoints measured. The present paper is the first to place the area of platelet-rich plasma-biomedical research and applications within an hormetic framework. The platelet-rich plasma area is also unique as it represents the application of the hormetic concept to the issue of complex biological mixtures.

Autologous Fat and Platelet-Rich Plasma Injections in Trapeziometacarpal Osteoarthritis: A Systematic Review and Meta-Analysis

BACKGROUND

For the treatment of carpometacarpal arthritis of the thumb, various therapies are used. Infiltration therapy with autologous substances such as platelet-rich plasma and autologous fat have recently gained increasing attention because of beneficial pain-reducing effects in arthritis and the associated regenerative potential. However, the extent of clinical evidence in this area and how well autologous substances work in terms of pain reduction and improvements in hand function remain unclear.

METHODS

A systematic review and meta-analysis were conducted to evaluate the current evidence and to provide more insight into pain reduction and improvement in hand function after infiltration of autologous substances. The authors identified 11 clinical trials, of which we included eight in the meta-analysis.

RESULTS

Autologous substances achieved a good and long-lasting pain reduction, which may also be accompanied by corresponding improvement in hand function. Autologous substances appear to be more effective than corticoid infiltrations. The infiltration of autologous fat seems to be particularly promising in more advanced stages of carpometacarpal arthritis of the thumb. Our meta-analysis showed a mean pain reduction of 2.4 to 3 in visual analogue scale score and a reduction of 18 to 19 points in the Disabilities of the Arm, Shoulder, and Hand questionnaire after infiltration with autologous substances.

CONCLUSION

Both platelet-rich plasma and autologous fat infiltration offer an efficient and long-lasting, minimally invasive therapy option in the treatment of carpometacarpal arthritis of the thumb.

Effects of Super-Activated Platelet Lysate on Early Healing of Tooth Extraction Sockets in Rats

Purpose

To evaluate the effect of super-activated platelet lysate (sPL) on wound healing of tooth extraction sockets in rats.

Methods

Rat models of the tooth extraction socket were established. Thirty-six rats were divided into control and sPL groups and sacrificed on days 7, 14, and 28 after tooth extraction. Bone formation in tooth extraction sockets were observed by microscopic computed tomography (micro-CT) and hematoxylin and eosin (HE) staining; osteoprotegerin (OPG), receptor activator of nuclear factor kappa-Β ligand (RANKL), interleukin 6(IL-6), and tumor necrosis factor-alpha (TNF-α) proteins were detected by immunohistochemistry; and chemokine and osteogenic gene expressions were detected by polymerase chain reaction (PCR).

Results

sPL accelerated soft tissue wound healing in the extraction socket of rats. Micro-CT showed that the amount of bone formation and bone volume fraction were higher in the sPL group than the control 14 days after extraction. HE staining showed promotion of the formation of bony trabeculae by sPL in the apical third of the extraction socket 7 days after extraction and more mature and organized bony trabeculae in the sPL group than the control 14 days after extraction; mature bony trabeculae filling most of the fossa with lesser bone porosity in the socket in the sPL group than the control 28 days after extraction. Immunohistochemistry showed that sPL induced OPG expressions 7 and 14 days after tooth extraction but did not affect the RANKL expression while transiently promoting the IL-6 expression 7 days after extraction. PCR showed that sPL promoted chemokine expressions 7 and 14 days after extraction. The expressions of osteogenesis-related factors were higher in the sPL group than the control 7 and 28 days after extraction, while the opposite trend was observed 14 days after extraction.

Conclusion

sPL has a transient pro-inflammatory effect and promotes soft tissue healing and bone formation during early wound healing of extraction sockets in rats.

Regeneration of temporomandibular joint using in vitro human stem cells: A review

Temporomandibular joint disorders (TMDs) range from gross anatomic deformities of the disc and hard tissue to functional disturbances. Traditional treatment of TMDs includes physical therapy, use of appliances, pharmacological, surgical and psychological interventions. However, during the late stage of TMDs, conventional management often results in inadequate relief of symptoms. Stem cell‐based tissue regeneration has been studied extensively in joint regeneration, including the Temporomandibular Joint (TMJ). This study aims to review the potential of various human stem cells (HSC) for the regeneration of the TMJ. In vitro studies using human mesenchymal stem cells cultured under different conditions to evaluate regeneration of TMJ related structures were searched on PubMed, EMBASE, Cochrane, and Web of Science up to March 2020. In vitro studies utilized several different types of stem cells under varying conditions. Increased osteogenesis and/or chondrogenesis were noted with stem cell interventions compared to control groups on Alkaline Phosphatase (ALP) activity, Col‐I, Col‐II, Col‐X, RUNX2, LPL, and Aggrecan mRNA expression. This review emphasizes the potential of stem cell therapies in the regeneration of TMJ‐related structures. However, further in vivo studies are required to evaluate the efficacy and safety of these therapies in humans.

Bone Morphogenetic Protein 7 Expression in Alveolar Bone Addition With Autologous Blood, Lyophilized Bone and Atelocollagen

BACKGROUND/AIM

The biomaterials used in guided bone regeneration have undergone significant diversification in recent years. This study aimed to evaluate alveolar bone addition and bone morphogenetic protein 7 (BMP7) expression using an improved autologous and xenogeneic biomaterial.

MATERIALS AND METHODS

Chronic marginal periodontitis was induced in sheep; the intervention group received bone addition as periodontal therapy, using a composite system with lyophilized bovine bone enriched with atelocollagen type 1, platelet-rich plasma and advanced platelet-rich fibrin (A-PRF). Six weeks after the intervention, the dentoalveolar structures were evaluated using hematoxylin-eosin and immunohistochemical staining, to evaluate bone addition and BMP7 expression.

RESULTS

The untreated sheep showed inflammation, periodontal ligament destruction, remnants of calculus and bacterial plaque as well as foreign bodies in the desmodontal space, without sings of repair. In the treated sheep, fibroblasts/fibrosis, cartilage and/or new bone, cellular cementum and desmodontium, along with remnants of biomaterial with various degrees of cellularity were observed. In the untreated group, the presence of BMP7 was found in osteoblasts and osteocytes while in the treated group, it was mainly found in the biomaterial remnants, while immunohistochemical staining was less intense in the newly formed osteo-periodontal tissues. Quantitative analysis using the Mann-Whitney U-test showed highly statistically significant differences between the two groups, demonstrating the efficiency of this composite system.

CONCLUSION

The current composite system meets all the necessary conditions for promising guided alveolar bone regeneration.

Combining Platelet-Rich Plasma Instillation With Core Decompression Improves Functional Outcome and Delays Progression in Early-Stage Avascular Necrosis of Femoral Head: a 4.5- to 6-Year Prospective Randomized Comparative Study

BACKGROUND

Avascular necrosis of femoral head is a debilitating disease frequently progressing to femoral head collapse and joint destruction. The efficacy of core decompression (CD) remains controversial.

METHODS

About 40 consecutive age-matched and gender-matched patients (53 hips) were randomized into 2 groups by computer-generated algorithm table in a prospective randomized double-blinded comparative study. Group A (platelet-rich plasma [PRP] with CD) included 19 patients (25 hips), and group B (CD only) included 21 patients (28 hips). Postoperative Harris Hip Score and magnetic resonance imaging to quantify the necrotic area by using modified Kerboul angle were done and evaluated. Mean follow-up was 64.3 months (range, 54-72) and 63.7 months (range, 56-72) in groups A and B, respectively.

RESULTS

There was statistically significant difference between PRP and control groups in pain score (P = .00), functional score (P = .02), and Harris Hip Score (P = .00) at final follow-up. There was no progression in stage 1 disease. Stage 2 disease showed 24% progression in group A and 43% progression in group B. The difference was statistically significant (P = .025). Survivorship from femoral head collapse, any procedure, and total hip arthroplasty was 84%/68% (P = .00), 76%/57% (P = .02), and 92%/78% (P = .01) in 2 groups, which was statistically significant.

CONCLUSION

PRP use after CD provides significant pain relief, better midterm functional outcome, retards the progression, and enhances the survivorship free from reoperation for hip arthroplasty and femoral head collapse in early stages of avascular necrosis of hip than CD alone.

An in vitro long-term study of cryopreserved umbilical cord blood-derived platelet-rich plasma containing growth factors-PDGF-BB, TGF-β, and VEGF

PURPOSE

Umbilical cord blood-derived platelet-rich plasma (UCB-PRP) containing growth factors has attracted attention as a biomaterial useful for regenerative medicine. The osteoblastic differentiation of umbilical cord-derived mesenchymal stromal cells (UC-MSCs) can be induced by UCB-PRP.

MATERIALS AND METHODS

Nine samples of UC and UCB were used to conduct an in vitro study that determined the contents of three growth factors (i.e., platelet-derived growth factor, transforming growth factor β-1, and vascular endothelial growth factor) and that examined, by staining with Alizarin red, their ability to induce the osteoblastic differentiation of UC-MSCs at the baseline, 3 months, and 3 years of cryopreservation.

RESULTS

The contents of growth factors in cryopreserved UCB-PRP were markedly elevated compared to those found in UCB at baseline. The samples of UCB that were added with cryopreserved UCB-PRP and those with bone morphogenetic protein-2 were stained granularly with Alizarin red, thus indicating the presence of calcium. The samples of UCB that were not added with UCB-PRP were not stained with Alizarin red. The above-mentioned contents and ability were maintained at 3 years of cryopreservation. Cryopreserved UCB-PRP possibly and advantageously induced the osteoblastic differentiation of UC-MSCs.

CONCLUSION

The potential clinical application of cryopreserved UCB-PRP to regenerative medicine was suggested.

Co-diagnoses of spondylolysis and femoroacetabular impingement: a case series of adolescent athletes

Locating the source of lumbopelvic–hip pain requires the consideration of multiple clinical pathways. Although low back pain has an incidence of 50% in the adolescent population, the pathophysiology in this population typically differs from that of other age groups. Dynamic mechanical impairments of the hip, such as femoroacetabular impingement, may contribute to the pathogenesis of adolescent low back pain. Eight adolescent male athletes who presented to a single provider with a primary complaint of low back pain with hip pain or motion loss on exam and were ultimately diagnosed with lumbar spondylolysis and dynamic mechanical hip issues between 2009 and 2011 were included. The age at spondylolysis diagnosis ranged from 15 to 19 years (mean ± standard deviation: 16.3 ± 1.3 years). Seven patients had cam-type impingement, whereas one presented with pincer-type impingement. All patients demonstrated either decreased internal rotation at 90 degrees of hip flexion and neutral abduction or pain on the Flexion Adduction Internal Rotation test on at least one of hip. All eight patients were treated initially with 6 weeks of physical therapy consisting of attempted restoration of hip motion and the graduated progression of hip and spine stabilization exercises. Five patients (62.5%) returned to sport at an average of 11.2 weeks (range: 6–16 weeks). For three patients (37.5%), hip pain and motion loss persisted, thus requiring surgery. All subjects had symptoms for at least 6 weeks, with 6 months as the longest duration. This report is the first documented series of adolescent athletes with co-diagnoses of spondylolysis and femoroacetabular impingement.

Study Information: This retrospective case series was approved by the Institutional Review Board at Hospital for Special Surgery.

Discovery of Heterotopic Bone-Inducing Activity in Hard Tissues and the TGF-β Superfamily

Bone is a unique organ because it can be experimentally induced in soft tissues by implanting a single growth factor, bone morphogenetic protein (BMP). Heterotopic bone-inducing activity was found in demineralized bone matrix in 1965. The characterization of this activity in bone enabled the purification and molecular cloning of BMPs and showed that they are members of the transforming growth factor-β (TGF-β) superfamily. Assay systems developed for this bone-inducing activity revealed the molecular mechanisms of the intracellular signaling of members of the superfamily, including BMPs. Moreover, they are being applied to elucidate molecular mechanisms and to develop novel therapeutics for a disease caused by an abnormality in BMP signaling.

Stem-cell therapy and platelet-rich plasma in regenerative medicines: A review on pros and cons of the technologies

Regenerative medicine encompasses new emerging branch of medical sciences that involves the functional restoration of tissues or organs caused by severe injuries or chronic diseases. Currently, there are two contending technologies that can repair and restore the damaged tissues, namely platelet-rich plasma (PRP)- and stem cell (SC)-based therapies. PRP is a component of blood that contains platelet concentrations above the normal level and includes platelet-related growth factors and plasma-derived fibrinogen. Platelets are the frontline healing response to injuries as they release growth factors for tissue repair. SCs, on the other hand, are the unspecialized, undifferentiated, immature cells that based on specific stimuli can divide and differentiate into specific type of cells and tissues. Differentiated SCs can divide and replace the worn out or damaged tissues to become tissue- or organ-specific cells with specialized functions. Despite these differences, both approaches rely on rejuvenating the damaged tissue. This review is focused on delineating the preparation procedures, similarities and disparities and advantages and disadvantages of PRP- and SC-based therapies.

Platelet-rich plasma inhibits RANKL-induced osteoclast differentiation through activation of Wnt pathway during bone remodeling

Platelet-rich plasma (PRP) is used in the clinic as an autologous blood product to stimulate bone regeneration and chondrogenesis. Numerous studies have demonstrated that PRP affects bone remodeling by accelerating osteoblast formation. With the research perspective focusing on osteoclasts, the present study established a mouse model of mandibular advancement to examine the effect of PRP on osteoclast differentiation induced by modification of the dynamics of the temporomandibular joint (TMJ). The lower incisors of the mice were trimmed by 1 mm and the resultant change in mandibular position during the process of eating induced condylar adaptation to this change. PRP significantly increased the bone mass and decreased osteoclastic activity, in vitro as well as in vivo. Mechanistically, the reduced expression of receptor activator of nuclear factor-κB ligand (RANKL)-induced differentiation marker genes, including nuclear factor of activated T-cells, cytoplasmic 1, c-fos and tartrate-resistant acid phosphatase, and that of the resorptive activity marker genes such as cathepsin k, carbonic anhydrase 2 and matrix metalloproteinase 9, indicated that PRP suppresses RANKL-induced osteoclast differentiation. A microarray analysis revealed that several genes associated with the Wnt pathway were differentially expressed, which indicated the involvement of this pathway in osteoclast differentiation. Furthermore, the activation of the Wnt pathway was verified by reverse transcription-quantitative polymerase chain reaction and immunoblot analysis of Dickkopf-related protein 1 and β-catenin. The results of the present study indicated that PRP inhibits osteoclast differentiation through activation of the Wnt pathway.

Efficacy of Humanized Mesenchymal Stem Cell Cultures for Bone Tissue Engineering: A Systematic Review with a Focus on Platelet Derivatives

Fetal bovine serum (FBS) is the most commonly used supplement for ex vivo expansion of human mesenchymal stem cells (hMSCs) for bone tissue engineering applications. However, from a clinical standpoint, it is important to substitute animal-derived products according to current good manufacturing practice (cGMP) guidelines. Humanized alternatives to FBS include three categories of products: human serum (HS), human platelet derivatives (HPDs)-including platelet lysate (PL) or platelet releasate (PR), produced by freeze/thawing or chemical activation of platelet concentrates, respectively, and chemically defined media (serum-free) (CDM). In this systematic literature review, the in vitro and in vivo osteogenic potential of hMSCs expanded in humanized (HS-, HPD-, or CDM-supplemented) media versus hMSCs expanded in FBS-supplemented media, was compared. In addition, PL and PR were compared in terms of their growth factor (GF)/cytokine-content and cell-culture efficacy. When using either 10-20% autologous or pooled HS, 3-10% pooled HPDs or CDM supplemented with GFs, in comparison with 10-20% FBS, a majority of studies reported similar or superior in vitro proliferation and osteogenic differentiation, and in vivo bone formation in ectopic or orthotopic rodent models. Moreover, a trend for higher GF content was observed in PL versus PR, although evidence for cell culture efficacy is limited. In summary, humanized supplements seem at least equally effective as FBS for hMSC expansion and osteogenic differentiation. Although pooled HPDs appear to be the most favorable supplement for large-scale hMSC expansion, further efforts are needed to standardize the preparation and composition of these products in compliance with cGMP standards.

Platelet-Rich Blood Derivatives for Stem Cell-Based Tissue Engineering and Regeneration

Platelet rich blood derivatives have been widely used in different fields of medicine and stem cell based tissue engineering. They represent natural cocktails of autologous growth factor, which could provide an alternative for recombinant protein based approaches. Platelet rich blood derivatives, such as platelet rich plasma, have consistently shown to potentiate stem cell proliferation, migration, and differentiation. Here, we review the spectrum of platelet rich blood derivatives, discuss their current applications in tissue engineering and regenerative medicine, reflect on their effect on stem cells, and highlight current translational challenges.

Bone Morphogenetic Proteins: Promising Molecules for Bone Healing, Bioengineering, and Regenerative Medicine

Bone morphogenetic proteins (BMPs), glycoproteins secreted by some cells, are members of the TGF-β superfamily that have been implicated in a wide variety of roles. Currently, about 20 different BMPs have been identified and grouped into subfamilies, according to similarities with respect to their amino acid sequences. It has been shown that BMPs are secreted growth factors involved in mesenchymal stem cell differentiation, also being reported to control the differentiation of cancer stem cells. BMPs initiate signaling from the cell surface by binding to two different receptors (R: Type I and II). The heterodimeric formation of type I R and II R may occur before or after BMP binding, inducing signal transduction pathways through SMADs. BMPs may also signal through SMAD-independent pathways via mitogen-activated protein kinases (ERK, p38MAPKs, JNK). BMPs may act in an autocrine or paracrine manner, being regulated by specific antagonists, namely: noggin and chordin. Genetic engineering allows the production of large amounts of BMPs for clinical use, and clinical trials have shown the benefits of FDA-approved recombinant human BMPs 2 and 7. Several materials from synthetic to natural sources have been tested as BMP carriers, ranging from hydroxyapatite, and organic polymers to collagen. Bioactive membranes doped with BMPs are promising options, acting to accelerate and enhance osteointegration. The development of smart materials, mainly based on biopolymers and bone-like calcium phosphates, appears to provide an attractive alternative for delivering BMPs in an adequately controlled fashion. BMPs have revealed a promising future for the fields of Bioengineering and Regenerative Medicine. In this chapter, we review and discuss the data on BMP structure, mechanisms of action, and possible clinical applications.

Stem cell regenerative therapy in alveolar cleft reconstruction

Achieving a successful and well-functioning reconstruction of craniofacial deformities still remains a challenge. As for now, autologous bone grafting remains the gold standard for alveolar cleft reconstruction. However, its aesthetic and functional results often remain unsatisfactory, which carries a long-term psychosocial and medical sequelae. Therefore, searching for novel therapeutic approaches is strongly indicated. With the recent advances in stem cell research, cell-based tissue engineering strategies move from the bench to the patients' bedside. Successful stem cell engineering employs a carefully selected stem cell source, a biodegradable scaffold with osteoconductive and osteoinductive properties, as well as an addition of growth factors or cytokines to enhance osteogenesis. This review highlights recent advances in mesenchymal stem cell tissue engineering, discusses animal models and case reports of stem cell enhanced bone regeneration, as well as ongoing clinical trials.

Adipose-derived stem cells and platelet-rich plasma for preventive treatment of bisphosphonate-related osteonecrosis of the jaw in a murine model

OBJECTIVES

The main challenge in treating bisphosphonate-related osteonecrosis of the jaw (BRONJ) is the absence of an effective established treatment. We aimed to compare different potentially preventive treatments for BRONJ after dental extractions in zoledronic acid (ZA)-treated animals. We studied the local application of different combinations of adipose-derived stem cells (ASCs) with or without previous stimulation with bone morphogenetic protein 2 (BMP-2) and platelet-rich plasma (PRP) in rats.

MATERIAL AND METHODS

Fifty-six male Wistar rats were treated with ZA for 9 weeks. Dental extractions were performed in the eighth week, and the animals were divided into 4 groups. In group 1 (n = 14), alveolar coverage with mucoperiosteal flap was performed. In group 2 (n = 14), PRP was applied over the sockets and covered with the flap. In group 3 (n = 15), allogeneic ASCs with PRP were applied and covered with the flap. In group 4 (n = 13), animals were treated with ASCs cultured with BMP-2, PRP, and flap coverage. Histologic, fluorescence, and radiologic studies of the maxillae were performed.

RESULTS

ASC-treated animals showed lower frequency of osteonecrosis (14% vs 50%, p = 0.007) and greater bone turnover (p = 0.024) and osteoclast count (p = 0.045) than those not receiving the ASC treatment.

CONCLUSIONS

In this high-risk model, ASC-based treatments seem to prevent BRONJ more effectively than mucosal flap with or without PRP. The combination of ASCs and PRP appears to be synergistic, and the addition of BMP-2 could further improve the results.

The use of platelet-rich plasma for the treatment of osteoarthritis

Osteoarthritis (OA) is the most common cause of disability in the United States. With an aging population, its incidence is only likely to rise. Articular cartilage has a poor capacity to heal. The advent of regenerative medicine has heralded a new approach to early treatment of degenerative conditions such as osteoarthritis by focusing on regenerating damaged tissue rather than focusing on replacement. Platelet-rich plasma (PRP) is one such treatment that has received much recent attention and has been used particularly for tendon healing. Recent studies have focused on assessing its use on degenerative conditions such as OA. In this article, we review the evidence for the pathologic basis for the use of PRP in OA and also the clinical outcomes pertaining to its use. Finally, we also consider reasons for the inconsistent clinical success pertaining to its use.

Formation of blood clot on biomaterial implants influences bone healing

The first step in bone healing is forming a blood clot at injured bones. During bone implantation, biomaterials unavoidably come into direct contact with blood, leading to a blood clot formation on its surface prior to bone regeneration. Despite both situations being similar in forming a blood clot at the defect site, most research in bone tissue engineering virtually ignores the important role of a blood clot in supporting healing. Dental implantology has long demonstrated that the fibrin structure and cellular content of a peri-implant clot can greatly affect osteoconduction and de novo bone formation on implant surfaces. This article reviews the formation of a blood clot during bone healing in relation to the use of platelet-rich plasma (PRP) gels. It is implicated that PRP gels are dramatically altered from a normal clot in healing, resulting in conflicting effect on bone regeneration. These results indicate that the effect of clots on bone regeneration depends on how the clots are formed. Factors that influence blood clot structure and properties in relation to bone healing are also highlighted. Such knowledge is essential for developing strategies to optimally control blood clot formation, which ultimately alter the healing microenvironment of bone. Of particular interest are modification of surface chemistry of biomaterials, which displays functional groups at varied composition for the purpose of tailoring blood coagulation activation, resultant clot fibrin architecture, rigidity, susceptibility to lysis, and growth factor release. This opens new scope of in situ blood clot modification as a promising approach in accelerating and controlling bone regeneration.

Experimental study of the effect of autologous platelet-rich plasma on the early phases of osteoinduction by allogenic demineralized bone matrix

PURPOSE

To evaluate the effect of autologous platelet-rich plasma (PRP) on the early phases of osteoinduction by allogenic demineralized bone matrix (DBM) in rabbit intramuscular positions.

MATERIALS AND METHODS

Allogenic DBM was produced from bones of 3 healthy rabbits. In each of 6 experimental animals, 0.3 mL autologous PRP was prepared and 2 muscle pouches were created, where 250 mg DBM + PRP (experimental sites) and 250 mg DBM without PRP (control sites) were randomly implanted. Animals were euthanized 3 weeks postoperatively.

RESULTS

Histologic examination revealed uneventful healing in all cases, whereas remineralization of the periphery of the bone graft particles was a constant finding. In both control and experimental sites, fibroblasts and other mesenchymal cells (probably osteoprogenitor cells and preosteoblasts) were observed. The main histological difference was the recolonization of the empty lacunae of the bone graft particles by osteocytes at the control sites. The degradation of the graft at the control sites was statistically significantly quicker, although a statistically significant difference regarding the amount of the newly formed fibrous connective tissue was not observed.

CONCLUSION

The present study demonstrated that in this experimental model, the addition of PRP to DBM had a negative effect on the early phases of osteoinduction at 3 weeks of observation.

Platelet rich plasma therapy: A comparative effective therapy with promising results in plantar fasciitis

Chronic muscle & tendon injuries are one of the problems which are encountered by human being since last long time. These injuries are generally repetitive strain injuries, commonly found in athletes. There are various treatments which include conservative methods in initial stages to surgery in later stages. On minimal invasive aspect Ultrasound-guided fenestration and tenotomy surgery has been used with good results as an effective treatment of chronic tendinopathies.(1,2) There are various injectable agents which were also researched including simple solutions such as hyperosmolar dextrose(3) (prolotherapy) to complex orthobiologic agents such as bone morphogenic protein,(4) but none have achieved uniform success. Platelet rich plasma (PRP) injection has emerged as a treatment alternative for many musculoskeletal conditions. We have done this study on sixty patients to evaluate & compare the effects of platelet rich plasma & steroid injection on patients with planter fasciitis. The results at the 1, 3 & 6 months were evaluated, which showed the good results with platelet rich plasma in comparison to steroid injections.

Human serum promotes osteogenic differentiation of human dental pulp stem cells in vitro and in vivo

Human dental pulp is a promising alternative source of stem cells for cell-based tissue engineering in regenerative medicine, for the easily recruitment with low invasivity for the patient and for the self-renewal and differentiation potential of cells. So far, in vitro culture of mesenchymal stem cells is usually based on supplementing culture and differentiation media with foetal calf serum (FCS). FCS is known to contain a great quantity of growth factors, and thus to promote cell attachment on plastic surface as well as expansion and differentiation. Nevertheless, FCS as an animal origin supplement may represent a potential means for disease transmission besides leading to a xenogenic immune response. Therefore, a significant interest is focused on investigating alternative supplements, in order to obtain a sufficient cell number for clinical application, avoiding the inconvenients of FCS use. In our study we have demonstrated that human serum (HS) is a suitable alternative to FCS, indeed its addition to culture medium induces a high hDPSCs proliferation rate and improves the in vitro osteogenic differentiation. Furthermore, hDPSCs-collagen constructs, pre-differentiated with HS-medium in vitro for 10 days, when implanted in immunocompromised rats, are able to restore critical size parietal bone defects. Therefore these data indicate that HS is a valid substitute for FCS to culture and differentiate in vitro hDPSCs in order to obtain a successful bone regeneration in vivo.

Effect of autologous platelet-rich plasma-releasate on intervertebral disc degeneration in the rabbit anular puncture model: a preclinical study

INTRODUCTION

Platelet-rich plasma (PRP) is a fraction of plasma in which several growth factors are concentrated at high levels. The active soluble releasate isolated following platelet activation of PRP (PRP-releasate) has been demonstrated to stimulate the metabolism of IVD cells in vitro. The in vivo effect of PRP-releasate on degenerated IVD remains unknown. The purpose of this study was to determine the reparative effects of autologous PRP-releasate on degenerated intervertebral discs (IVDs).

METHODS

To induce disc degeneration, New Zealand white rabbits (n = 12) received anular puncture in two noncontiguous discs. Autologous PRP and PPP (platelet-poor plasma) were isolated from fresh blood using two centrifugation techniques. Four weeks after the initial puncture, releasate isolated from clotted PPP or PRP (PPP- or PRP-releasate), or phosphate-buffered saline (PBS; control) was injected into the punctured discs. Disc height, magnetic resonance imaging (MRI) T2-mapping and histology were assessed.

RESULTS

Anular puncture produced a consistent disc narrowing within four weeks. PRP-releasate induced a statistically significant restoration of disc height (PRP vs. PPP and PBS, P<0.05). In T2-quantification, the mean T2-values of the nucleus pulposus (NP) and anulus fibrosus (AF) of the discs were not significantly different among the three treatment groups. Histologically, the number of chondrocyte-like cells was significantly higher in the discs injected with PRP-releasate compared to that with PBS.

CONCLUSIONS

The administration of active PRP-releasate induced a reparative effect on rabbit degenerated IVDs. The results of this study suggest that the use of autologous PRP-releasate is safe and can lead to a clinical application for IVD degeneration.

Platelet-rich plasma therapy - future or trend?

Chronic complex musculoskeletal injuries that are slow to heal pose challenges to physicians and researchers alike. Orthobiologics is a relatively newer science that involves application of naturally found materials from biological sources (for example, cell-based therapies), and offers exciting new possibilities to promote and accelerate bone and soft tissue healing. Platelet-rich plasma (PRP) is an orthobiologic that has recently gained popularity as an adjuvant treatment for musculoskeletal injuries. It is a volume of fractionated plasma from the patient's own blood that contains platelet concentrate. The platelets contain alpha granules that are rich in several growth factors, such as platelet-derived growth factor, transforming growth factor-β, insulin-like growth factor, vascular endothelial growth factor and epidermal growth factor, which play key roles in tissue repair mechanisms. PRP has found application in diverse surgical fields to enhance bone and soft-tissue healing by placing supra-physiological concentrations of autologous platelets at the site of tissue damage. The relative ease of preparation, applicability in the clinical setting, favorable safety profile and possible beneficial outcome make PRP a promising therapeutic approach for future regenerative treatments. However, there is a large knowledge gap in our understanding of PRPs mechanism of action, which has raised skepticism regarding its potential efficacy and use. Thus, the aim of this review is to describe the various factors proposed to contribute to the biological activity of PRP, and the published pre-clinical and clinical evidence to support it. Additionally, we describe the current techniques and technology for PRP preparation, and review the present shortcomings of this therapy that will need to be overcome if it is to gain broad acceptance.

The effect of platelet rich plasma from bone marrow aspirate with added bone morphogenetic protein-2 on the Achilles tendon-bone junction in rabbits

Background

To determine if exogenously injected bone marrow derived platelet-rich plasma (PRP) plus bone morphogenetic protein (BMP)-2 could accelerate the healing of bone-tendon junction injuries and increase the junction holding strength during the early regeneration period.

Methods

A direct injury model of the bone-tendon junction was made using an Achilles tendon-calcaneus bone junction in a rabbit. In the PRP/BMP-2/fibrin group, 0.05 mL of bone marrow derived PRP and 100 ng/mL of BMP-2 both incorporated into 0.1 mL of fibrin glue were injected into Achilles tendon-calcaneus bone junctions. The effect of the intervention was tested by comparing the results of an intervention group to a control group. The results of biomechanical testing, and histological and gross analyses were compared between the 2 groups at the following time points after surgery: 2 weeks, 4 weeks, and 8 weeks.

Results

Histologic examinations showed that woven bone developed in tendon-bone junctions at 2 weeks after surgery in the PRP/BMP-2/fibrin group. Mechanical test results showed no significant difference between the PRP/BMP-2/fibrin and control groups at 2 and 4 weeks after surgery, but the mean maximal load in the PRP/BMP-2/fibrin group was significantly higher than in the control group (p < 0.05) at 8 weeks after surgery.

Conclusions

Bone marrow derived PRP and BMP-2 in fibrin glue accelerated healing in a rabbit model of tendon-bone junction injury.

Acute skeletal injury is necessary for human adipose-derived stromal cell-mediated calvarial regeneration

BACKGROUND

Studies have demonstrated that human adipose-derived stromal cells (ASCs) are able to repair acute calvarial injuries. The more clinically relevant repair of an established skeletal defect, however, has not been addressed. The authors sought to determine whether human ASCs could heal chronic (established) calvarial defects.

METHODS

Critical-sized (4 mm) mouse parietal defects were created. Human ASCs were engrafted either immediately postoperatively (acute defect) or 8 weeks following defect creation (established defect). Methods of analysis included microcomputer tomography scans, histology, and in situ hybridization. Finally, human ASCs were treated in vitro with platelet-rich plasma to simulate an acute wound environment; proliferation and osteogenic differentiation were assessed (alkaline phosphatase, alizarin red, and quantitative reverse transcriptase polymerase chain reaction).

RESULTS

Nearly complete osseous healing was observed when calvarial defects were immediately engrafted with human ASCs. In contrast, when human ASCs were engrafted into established defects, little bone formation occurred. Histological analysis affirmed findings by microcomputer tomography, showing more robust staining for alkaline phosphatase and picrosirius red in an acute than in an established human ASC-engrafted defect. In situ hybridization and quantitative reverse transcriptase polymerase chain reaction showed an increase in bone morphogenetic protein (BMP) expression (BMP-2, BMP-4, and BMP-7) acutely following calvarial defect creation. Finally, in vitro treatment of human ASCs with platelet-rich plasma enhanced osteogenic differentiation and increased BMP-2 expression.

CONCLUSIONS

Although human ASCs can be utilized to heal an acute mouse calvarial defect, they do not enhance healing of an established (or chronic) defect. Endogenous BMP signaling activated after injury may explain these differences in healing. Platelet-rich plasma enhances osteogenic differentiation of human ASCs in vitro and may prove a promising therapy for future skeletal tissue engineering efforts.

Musculoskeletal applications of platelet-rich plasma: fad or future?

OBJECTIVE

The purpose of this article is to detail the biology of platelet-rich plasma (PRP), critically review the existing literature, and discuss future research applications needed to adopt PRP as a mainstay treatment method for common musculoskeletal injuries.

CONCLUSION

Any promising minimally invasive therapy such as PRP deserves further investigation to avoid surgery. Diagnostic imaging outcome assessments, including ultrasound-guided needle precision, should be included in future investigations.

The use of platelet rich plasma, bone morphogenetic protein-2 and different scaffolds in oral and maxillofacial surgery - literature review in comparison with own clinical experience

Objectives

The purpose of this article was to review and critically assess the use of platelet rich plasma, recombinant human bone morphogenetic protein-2 and different scaffolds (i.e. tricalciumphosphate, polycaprolactone, demineralized bone matrix and anorganic bovine bone mineral) in oral and maxillofacial surgery comparing the relevant literature and own clinical experience.

Material and Methods

A literature review was conducted using MEDLINE, MEDPILOT and COCHRANE DATABASE OF SYSTEMATIC REVIEWS. It concentrated on manuscripts and overviews published in the last five years (2006-2010). The key terms employed were platelet rich plasma, bone morphogenetic proteins and their combinations with the above mentioned scaffolds. The results of clinical studies and animal trials were especially emphasized. The statements from the literature were compared with authors’ own clinical data.

Results

New publications and overviews demonstrate the advantages of platelet rich plasma in bone regeneration. The results from the literature review were discussed and compared with the publications detailing authors' own experiences.

Conclusions

A favourable outcome concerning newly grown bone was achieved combining platelet rich plasma in addition to optimal matrices with or without recombinant human bone morphogenetic protein-2, depending on the clinical case. As a consequence, the paradigm shift from transplantation of autogenous bone to bone tissue engineering appears promising.

The effect of platelet-rich plasma in vitro on primary cells: rat osteoblast-like cells and human endothelial cells

The aim of this study was to evaluate the effects of standardized platelet-rich plasma (PRP) concentrates from 10 human donors on cellular behavior. The standardized PRPs used were fivefold average and fivefold maximum baseline values in whole blood. Both these standardized PRPs were characterized by determining platelet numbers and subsequently growth factor concentrations in activated PRPs, called PRP derivatives. Platelet numbers in both types of standardized PRPs were significantly increased compared with whole blood. Further, both PRP derivatives contained significantly higher concentrations of platelet-derived growth factor-AA, platelet-derived growth factor-AB, and transforming growth factor-beta 1. Vascular endothelial growth factor concentrations were significantly elevated in only the most concentrated PRP derivative. Cell culture experiments with osteoblast-like cells showed that both PRP derivatives stimulated cell proliferation without inducing cell differentiation, whereas tube formation in endothelial cell cultures was significantly increased by adding low volume percentages of PRP derivative (2%&#x2013;8%). Consequently, it can be concluded that there is no direct relationship between the number of platelets and the level of growth factors released from these platelets. PRP derivatives have the potency to stimulate angiogenesis dose dependently, while lacking the capacity to induce osteogenic differentiation. Yet, the proliferation of osteoblast-like cells can significantly be enhanced by supplementation of PRP derivatives.

Current concepts for the use of platelet-rich plasma in the foot and ankle

Platelet-rich plasma (PRP) injections have been used and studied since the 1970s. Its use has become more popularized over the last several years in the treatment of foot and ankle injuries. Platelets are a normal product found in the clotting cascade and inflammatory process of healing. They produce granules that release growth factors that promote healing. PRP works by increasing the concentration of platelets, thereby increasing the concentration of growth factors and increasing healing potential. PRP has an advantage over many tissue engineering products in that it is autologous. It has been studied and used for the treatment of tendon injuries, chronic wounds, ligamentous injuries, cartilage injuries, muscle injuries, and bone augmentation. The results from in vitro and in vivo studies in foot and ankle injuries are promising. The applications for treatment in the foot and ankle may be broader than once thought.

Platelet rich plasma to facilitate wound healing following tooth extraction

Following tooth removal bone formation normally takes 16 weeks and may result in less than adequate volume for the necessary reconstruction. Platelet rich plasma (PRP) has been promoted as an effective method for improving bone formation. Its use is often expensive, time consuming, or not clinically convenient for the patient and/or clinician. This study examines a simple method for obtaining a "Buffy Coat"-PRP (BC-PRP) and its effect on bone healing following the removal of bilateral mandibular 3rd molars. Subtraction digital radiography and CT scan analysis were used to track changes in radiographic density at PRP treated sites in comparison to ipsilateral non-PRP treated sites. PRP treated sites demonstrated early and significant increased radiographic density over baseline measurements following tooth removal. The greatest benefit of PRP is during the initial 2-week postoperative healing time period (P < .001). During weeks 3 though 12, BC-PRP treatment resulted in significant (P < .0001) increases in bone density compared to control, but there was no significant interaction between time and treatment (P > .05). For the entire time period (0-25 weeks) PRP treatment was significant (P < .0001) and time was significant (P < .0001) but there was no significant interaction (P > .05) between the effect of PRP treatment and time. It required 6 weeks for control extraction sites to reach comparable bone density that PRP treated sites achieved at week 1. Postoperative pain, bleeding, and numbness were not significantly affected by BC-PRP application. Results suggest that this simple technique may be of value to clinicians performing oral surgery by facilitating bone regeneration following tooth extraction.

Bone morphogenetic proteins and tissue engineering: future directions

As long as bone repair and regeneration is considered as a complex clinical condition, the administration of more than one factor involved in fracture healing might be necessary. The effectiveness or not of bone morphogenetic proteins (BMPs) in association with other growth factors and with mesenchymal stem cells in bone regeneration for fracture healing and bone allograft integration is of great interest to the scientific community. In this study we point out possible future developments in BMPs, concerning research and clinical applications.

Bone and wound healing augmentation with platelet-rich plasma

Over the past two decades, autologous platelets that have been sequestered, concentrated, and mixed with thrombin to generate growth factor-concentrated platelet-rich plasma for application to bone and wounds to aide healing have been a subject of great interest. This article reviews the literature related to the use of autologous platelet-rich plasma in bone and wound healing, and reviews the processes necessary to secure a high concentration of viable platelets. Although not yet definitive, autologous platelet-rich plasma has been shown to be safe, reproducible, and effective in mimicking the natural process of bone and wound healing.

The biology of platelet-rich plasma and its application in trauma and orthopaedic surgery: a review of the literature

Although mechanical stabilisation has been a hallmark of orthopaedic surgical management, orthobiologics are now playing an increasing role. Platelet-rich plasma (PRP) is a volume of plasma fraction of autologous blood having platelet concentrations above baseline. The platelet alpha granules are rich in growth factors that play an essential role in tissue healing, such as transforming growth factor-beta, vascular endothelial growth factor, and platelet-derived growth factor. PRP is used in various surgical fields to enhance bone and soft-tissue healing by placing supraphysiological concentrations of autologous platelets at the site of tissue damage. The easily obtainable PRP and its possible beneficial outcome hold promise for new regenerative treatment approaches. The aim of this literature review was to describe the bioactivities of PRP, to elucidate the different techniques for PRP preparation, to review animal and human studies, to evaluate the evidence regarding the use of PRP in trauma and orthopaedic surgery, to clarify risks, and to provide guidance for future research.

Quantification of bone mass gain in response to the application of biphasic bioceramics and platelet concentrate in critical-size bone defects

Biphasic bioceramics have been widely indicated for bone reconstruction; however, the real gain in bone mass due to the presence of such biomaterials has not been established yet nor the advantages of its association with platelet concentrate. This study aims at quantifying the volume of bone matrix, osteoblasts, osteocytes, blood vessels and adipose tissue after the application of a biphasic bioceramics composed of 65% hydroxyapatite and 35% beta-tricalcium phosphate. Critical-size bone defects were produced in rabbit femora and reconstructed with bioceramics only, with bioceramics combined with platelet concentrate, with platelet concentrate alone, and with no treatment (blood clot). The quantitative evaluation was performed on histological sections using histomorphometry. Our data provide original evidence that consolidates the indication of bioceramics for clinical bone loss reconstruction. The application of biphasic bioceramics alone led to major bone mass gain and was followed by its association with platelet concentrate. On the other hand, platelet concentrate can contribute to the augmentation and maintenance of the adipose tissue, representing a new field for future applications in plastic surgery.

Treatment with a growth factor-protein mixture inhibits formation of mineralized nodules in osteogenic cell cultures grown on titanium

Despite wide clinical application, the efficacy of platelet-rich plasma (PRP) for repairing bone defects and enhancing osseointegration of metal implants is still subject of debate. This study aimed to evaluate the effects of a well-defined PRP-like mixture containing platelet-derived growth factor-BB, transforming growth factor (TGF)-beta1, TGF-beta2, albumin, fibronectin, and thrombospondin [growth factors (GFs) + proteins] on the development of the osteogenic phenotype on titanium (Ti) in vitro. Human alveolar bone-derived osteoblastic cells were subcultured on Ti discs and exposed during the first 7 days to osteogenic medium supplemented with GFs + proteins and to osteogenic medium alone thereafter up to 14 days. Control cultures were exposed to only osteogenic medium. Dose-response experiments were carried out using rat primary calvarial cells exposed to GFs + proteins and 1:10 or 1:100 dilutions of the mixture. Treated human-derived cell cultures exhibited a significantly higher number of cycling cells at days 1 and 4 and of total cells at days 4 and 7, significantly reduced alkaline phosphatase (ALP) activity at days 4, 7, and 10, and no Alizarin red-stained areas (calcium deposits) at day 14, indicating an impairment in osteoblast differentiation. Although the 1:10 and 1:100 dilutions of the mixture restored the proliferative activity of rat-derived osteogenic cells to control levels and promoted a significant increase in ALP activity at day 10 compared with GFs + proteins, mineralized nodule formation was only observed with the 1:100 dilution ( approximately 50% of the control). These results showed that a PRP-like protein mixture inhibits development of the osteogenic phenotype in both human and rat osteoblastic cell cultures grown on Ti.

The effect of human osteoblasts on proliferation and neo-vessel formation of human umbilical vein endothelial cells in a long-term 3D co-culture on polyurethane scaffolds

Angiogenesis is a key element in early wound healing and is considered important for tissue regeneration and for directing inflammatory cells to the wound site. The improvement of vascularization by implementation of endothelial cells or angiogenic growth factors may represent a key solution for engineering bone constructs of large size. In this study, we describe a long-term culture environment that supports the survival, proliferation, and in vitro vasculogenesis of human umbilical vein endothelial cells (HUVEC). This condition can be achieved in a co-culture model of HUVEC and primary human osteoblasts (hOB) employing polyurethane scaffolds and platelet-rich plasma in a static microenvironment. We clearly show that hOB support cell proliferation and spontaneous formation of multiple tube-like structures by HUVEC that were positive for the endothelial cell markers CD31 and vWF. In contrast, in a monoculture, most HUVEC neither proliferated nor formed any apparent vessel-like structures. Immunohistochemistry and quantitative PCR analyses of gene expression revealed that cell differentiation of hOB and HUVEC was stable in long-term co-culture. The three-dimensional, FCS-free co-culture system could provide a new basis for the development of complex tissue engineered constructs with a high regeneration and vascularization capacity.