ACE configurator for ELISpot: optimizing combinatorial design of pooled ELISpot assays with an epitope similarity model

The enzyme-linked immunosorbent spot (ELISpot) assay is a powerful in vitro immunoassay that enables cost-effective quantification of antigen-specific T-cell reactivity. It is used widely in the context of cancer and infectious diseases to validate the immunogenicity of predicted epitopes. While technological advances have kept pace with the demand for increased throughput, efforts to increase scale are bottlenecked by current assay design and deconvolution methods, which have remained largely unchanged. Current methods for designing pooled ELISpot experiments offer limited flexibility of assay parameters, lack support for high-throughput scenarios and do not consider peptide identity during pool assignment. We introduce the ACE Configurator for ELISpot (ACE) to address these gaps. ACE generates optimized peptide-pool assignments from highly customizable user inputs and handles the deconvolution of positive peptides using assay readouts. In this study, we present a novel sequence-aware pooling strategy, powered by a fine-tuned ESM-2 model that groups immunologically similar peptides, reducing the number of false positives and subsequent confirmatory assays compared to existing combinatorial approaches. To validate ACE's performance on real-world datasets, we conducted a comprehensive benchmark study, contextualizing design choices with their impact on prediction quality. Our results demonstrate ACE's capacity to further increase precision of identified immunogenic peptides, directly optimizing experimental efficiency. ACE is freely available as an executable with a graphical user interface and command-line interfaces at https://github.com/pirl-unc/ace.

LENS: Landscape of Effective Neoantigens Software

MOTIVATION

Elimination of cancer cells by T cells is a critical mechanism of anti-tumor immunity and cancer immunotherapy response. T cells recognize cancer cells by engagement of T cell receptors with peptide epitopes presented by major histocompatibility complex molecules on the cancer cell surface. Peptide epitopes can be derived from antigen proteins coded for by multiple genomic sources. Bioinformatics tools used to identify tumor-specific epitopes via analysis of DNA and RNA-sequencing data have largely focused on epitopes derived from somatic variants, though a smaller number have evaluated potential antigens from other genomic sources.

RESULTS

We report here an open-source workflow utilizing the Nextflow DSL2 workflow manager, Landscape of Effective Neoantigens Software (LENS), which predicts tumor-specific and tumor-associated antigens from single nucleotide variants, insertions and deletions, fusion events, splice variants, cancer-testis antigens, overexpressed self-antigens, viruses, and endogenous retroviruses. The primary advantage of LENS is that it expands the breadth of genomic sources of discoverable tumor antigens using genomics data. Other advantages include modularity, extensibility, ease of use, and harmonization of relative expression level and immunogenicity prediction across multiple genomic sources. We present an analysis of 115 acute myeloid leukemia samples to demonstrate the utility of LENS. We expect LENS will be a valuable platform and resource for T cell epitope discovery bioinformatics, especially in cancers with few somatic variants where tumor-specific epitopes from alternative genomic sources are an elevated priority.

AVAILABILITY AND IMPLEMENTATION

More information about LENS, including code, workflow documentation, and instructions, can be found at (https://gitlab.com/landscape-of-effective-neoantigens-software).

Prospects on the Potential In Vitro Regenerative Features of Mechanically Treated-Adipose Tissue for Osteoarthritis Care

Gathering a better grasp on the adipose stromal vascular fraction (SVF) is demanding among clinicians for osteoarthritis (OA) care because of its promising but multifaceted clinical outcomes. The aim of this preclinical in vitro study was to test whether the mechanical approach with Hy-Tissue SVF system, a class IIa CE marked device of adipose tissue micro-fragmentation, influences the biological features and functions of SVF. We compared mechanical generated-SVF (mSVF) with the enzymatic generated-SVF (eSVF) by testing cell survival, phenotype, differentiation, and paracrine properties using ELISA assays. Both adipose SVF showed 80% viable cells and enrichment for CD-44 marker. The mSVF product preserved the functions of cell populations within the adipose tissue; however, it displayed lowered nucleated cell recovery and CFU-F than eSVF. As for multipotency, mSVF and eSVF showed similar differentiation commitment for osteochondral lineages. Both adipose SVF exhibited an increased release of VEGF, HGF, IGF-1 and PDGF-bb, involved in pathways mediating osteochondral repair and cell migration. Both mSVF and eSVF also displayed high release for the anti-inflammatory cytokine IL-10. After in vitro culture, supernatants from both mSVF and eSVF groups showed a low release of cytokines except for IL-10, thereby giving evidence of functional changes after culture expansion. In this study, mSVF showed active cell populations in the adipose tissue comparable to eSVF with excellent survival, differentiation and paracrine properties under a new mechanical adipose tissue micro-fragmentation system; thereby suggesting its potential use as a minimally invasive technique for OA treatment.

Landscape and selection of vaccine epitopes in SARS-CoV-2

BACKGROUND

Early in the pandemic, we designed a SARS-CoV-2 peptide vaccine containing epitope regions optimized for concurrent B cell, CD4+ T cell, and CD8+ T cell stimulation. The rationale for this design was to drive both humoral and cellular immunity with high specificity while avoiding undesired effects such as antibody-dependent enhancement (ADE).

METHODS

We explored the set of computationally predicted SARS-CoV-2 HLA-I and HLA-II ligands, examining protein source, concurrent human/murine coverage, and population coverage. Beyond MHC affinity, T cell vaccine candidates were further refined by predicted immunogenicity, sequence conservation, source protein abundance, and coverage of high frequency HLA alleles. B cell epitope regions were chosen from linear epitope mapping studies of convalescent patient serum, followed by filtering for surface accessibility, sequence conservation, spatial localization near functional domains of the spike glycoprotein, and avoidance of glycosylation sites.

RESULTS

From 58 initial candidates, three B cell epitope regions were identified. From 3730 (MHC-I) and 5045 (MHC-II) candidate ligands, 292 CD8+ and 284 CD4+ T cell epitopes were identified. By combining these B cell and T cell analyses, as well as a manufacturability heuristic, we proposed a set of 22 SARS-CoV-2 vaccine peptides for use in subsequent murine studies. We curated a dataset of ~ 1000 observed T cell epitopes from convalescent COVID-19 patients across eight studies, showing 8/15 recurrent epitope regions to overlap with at least one of our candidate peptides. Of the 22 candidate vaccine peptides, 16 (n = 10 T cell epitope optimized; n = 6 B cell epitope optimized) were manually selected to decrease their degree of sequence overlap and then synthesized. The immunogenicity of the synthesized vaccine peptides was validated using ELISpot and ELISA following murine vaccination. Strong T cell responses were observed in 7/10 T cell epitope optimized peptides following vaccination. Humoral responses were deficient, likely due to the unrestricted conformational space inhabited by linear vaccine peptides.

CONCLUSIONS

Overall, we find our selection process and vaccine formulation to be appropriate for identifying T cell epitopes and eliciting T cell responses against those epitopes. Further studies are needed to optimize prediction and induction of B cell responses, as well as study the protective capacity of predicted T and B cell epitopes.

Biosynthetic scaffolds for partial meniscal loss: A systematic review from animal models to clinical practice

Acute or degenerative meniscus tears are the most common knee lesions. Meniscectomy provides symptomatic relief and functional recovery only in the short- to mid-term follow-up but significantly increases the risk of osteoarthritis. For this reason, preserving the meniscus is key, although it remains a challenge. Allograft transplants present many disadvantages, so during the last 20 years preclinical and clinical research focused on developing and investigating meniscal scaffolds. The aim of this systematic review was to collect and evaluate all the available evidence on biosynthetic scaffolds for meniscus regeneration both in vivo and in clinical studies. Three databases were searched: 46 in vivo preclinical studies and 30 clinical ones were found. Sixteen natural, 15 synthetic, and 15 hybrid scaffolds were studied in vivo. Among them, only 2 were translated into clinic: the Collagen Meniscus Implant, used in 11 studies, and the polyurethane-based scaffold Actifit®, applied in 19 studies. Although positive outcomes were described in the short- to mid-term, the number of concurrent procedures and the lack of randomized trials are the major limitations of the available clinical literature. Few in vivo studies also combined the use of cells or growth factors, but these augmentation strategies have not been applied in the clinical practice yet. Current solutions offer a significant but incomplete clinical improvement, and the regeneration potential is still unsatisfactory. Building upon the overall positive results of these “old” technologies to address partial meniscal loss, further innovation is urgently needed in this field to provide patients better joint sparing treatment options.

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Animal studies employed natural, synthetic and hybrid natural/synthetic scaffolds.

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Only in a few animal studies scaffold augmentation with cells or GFs was tested.

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Only two meniscal scaffolds have reached clinical application: CMI and Actifit.

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Clinical results are promising, but complete meniscus regeneration has not been achieved.

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There is urgent need for technological innovation in the field of meniscal regeneration.

Spinal fusion procedures in the adult and young population: a systematic review on allogenic bone and synthetic grafts when compared to autologous bone

This systematic review aims to compare clinical evidences related to autologous iliac crest bone graft (ICBG) and non-ICBG (local bone) with allografts and synthetic grafts for spinal fusion procedures in adult and young patients. A systematic search was carried out in three databases (PubMed, Scopus, Web of Science, Cochrane Central Register of Controlled Trials) to identify clinical studies in the last 10 years. The initial search retrieved 1085 studies, of which 24 were recognized eligible for the review. Twelve studies (4 RCTs, 5 prospective, 3 retrospective) were focused on lumbar spine, 9 (2 RCTs, 2 prospective, 4 retrospective, 1 case-series) on cervical spine and 3 (1 RCT, 2 retrospective) on spinal fusion procedures in young patients. Calcium phosphate ceramics, allografts, bioglasses, composites and polymers have been clinically investigated as substitutes of autologous bone in spinal fusion procedures. Of the 24 studies included in this review, only 1 RCT on cervical spine was classified with high level of evidence (Class I) and showed low risk of bias. This RCT demonstrated the safety and efficacy of the proposed treatment, a composite bone substitute, that results in similar and on some metrics superior outcomes compared with local autograft bone. Almost all other studies showed moderately or, more often, high incidence of bias (Class III), thus preventing ultimate conclusion on the hypothesized beneficial effects of allografts and synthetic grafts. This review suggests that users of allografts and synthetic grafting should carefully consider the scientific evidence concerning efficacy and safety of these bone substitutes, in order to select the best option for patient undergoing spinal fusion procedures.

Relevance of humanized three-dimensional tumor tissue models: a descriptive systematic literature review

Despite numerous advances in tumor screening, diagnosis, and treatment, to date, tumors remain one of the leading causes of death, principally due to metastasis and the physiological damage produced by tumor growth. Among the main limits related to the study of tumor physiology there is the complex and heterogeneity nature of its environment and the absence of relevant, simple and inexpensive models able to mimic the biological processes occurring in patients allowing the correct clinical translation of results. To enhance the understanding of the mechanisms of tumors and to develop and evaluate new therapeutic approaches the set-up of advanced and alternative models is mandatory. One of the more translational approaches seems to be the use of humanized three-dimensional (3D) tissue culture. This model allows to accurately mimic tumor morphology and biology, maintaining the native microenvironment without any manipulation. However, little is still known on the real clinical relevance of these models for the study of tumor mechanisms and for the screening of new therapy. The aim of this descriptive systematic literature review was to evaluate and summarize the current knowledge on human 3D tumor tissue culture models. We reviewed the strategies employed by researchers to set-up these systems, also considering the different approaches and culture conditions used. All these aspects greatly contribute to the existing knowledge on tumors, providing a specific link to clinical scenarios and making the humanized 3D tumor tissue models a more attractive tool both for researchers and clinicians.

Use of Antibiotic Loaded Biomaterials for the Management of Bone Prosthesis Infections: Rationale and Limits

BACKGROUND

Periprosthetic joint infection still represents a challenging issue for the orthopedic community. In the United States approximately a million joint arthroplasties are performed each year, with infection rates ranging from 1 to 2%: revisions has significant implications on health care costs and appropriate resource management. The use of locally applied antibiotics as a prophylaxis measure or as a component of the therapeutic approach in primary or revision surgery is finalized at eliminating any microorganism and strengthening the effectiveness of systemic therapy.

OBJECTIVE

The present review of clinical and preclinical in vivo studies tried to identify advantages and limitations of the materials used in the clinical orthopedic practice and discuss developed biomaterials, innovative therapeutic approaches or strategies to release antibiotics in the infected environment.

METHODS

A systematic search was carried out by two independent observers in two databases (www.pubmed.com and www.scopus.com) in order to identify pre-clinical and clinical reports in the last 10 years.

RESULTS

71 papers were recognized eligible: 15 articles were clinical studies and 56 in vivo studies.

CONCLUSION

Polymethylmethacrylate was the pioneer biomaterial used to manage infections after total joint replacement. Despite its widespread use, several issues still remain debated: the methods to combine materials and antibiotics, the choice of antibiotics, releasing kinetics and antibiotics efficacy. In the last years, the interest was directed towards the selection of different antibiotics, loaded in association with more than only one class and biomaterials with special focus on delivery systems as implant surface coatings, hydrogels, ceramics, micro-carriers, microspheres or nanoparticles.

Deregulated miRNAs in osteoporosis: effects in bone metastasis

Starting from their role exerted on osteoblast and osteoclast differentiation and activity pathways, microRNAs (miRNAs) have been recently identified as regulators of different processes in bone homeostasis. For this purpose, in a recent review, we highlighted, as deregulated miRNAs could be involved in different bone diseases such as osteoporosis. In addition, recent studies supported the concept that osteoporosis-induced bone alterations might offer a receptive site for cancer cells to form bone metastases, However, to date, no data on specific-shared miRNAs between osteoporosis and bone metastases have been considered and described to clarify the evidence of this link. The main goal of this review is to underline as deregulated miRNAs in osteoporosis may have specific roles in the development of bone metastases. The review showed that several circulating osteoporotic miRNAs could facilitate tumor progression and bone-metastasis formation in several tumor types, i.e., breast cancer, prostate cancer, non-small-cell lung cancer, esophageal squamous cell carcinoma, and multiple myeloma. In detail, serum up-regulation of pro-osteoporotic miRNAs, as well as serum down-regulation of anti-osteoporotic miRNAs are common features of all these tumors and are able to promote bone metastasis. These results are of key importance and could help researcher and clinicians to establish new therapeutic strategies connected with deregulation of circulating miRNAs and able to interfere with pathogenic processes of osteoporosis, tumor progressions, and bone-metastasis formation.

Deregulated miRNAs in bone health: Epigenetic roles in osteoporosis

MicroRNA (miRNA) has shown to enhance or inhibit cell proliferation, differentiation and activity of different cell types in bone tissue. The discovery of miRNA actions and their targets has helped to identify them as novel regulations actors in bone. Various studies have shown that miRNA deregulation mediates the progression of bone-related pathologies, such as osteoporosis. The present review intends to give an exhaustive overview of miRNAs with experimentally validated targets involved in bone homeostasis and highlight their possible role in osteoporosis development. Moreover, the review analyzes miRNAs identified in clinical trials and involved in osteoporosis.

Link between estrogen deficiency osteoporosis and susceptibility to bone metastases: A way towards precision medicine in cancer patients

Different fields of cancer management consider bone health to be of increasing clinical importance for patients: 1) presence of bone metastases in many solid tumors, 2) use of bone-targeted treatments in the reduction of bone metastasis, 3) effects of cancer treatment on reproductive hormones, critical for normal bone remodeling maintenance. Additionally, bone microenvironment is further complicated by the decline of ovarian sex steroid production and by the related increase in inflammatory factors linked to menopause, which result in accelerated bone loss and increased risk of osteoporosis (OP). Similarly, cancers and metastasis to bone showed a close relationship with sex hormones (particularly estrogen). Thus, these findings raise a question: Could pre-existing estrogen deficiency OP promote and/or influence cancer cell homing and tumor growth in bone? Although some preclinical and clinical evidence exists, it is mandatory to understand this aspect that would be relevant in the clinical theatre, where physicians need to understand the treatments available to reduce the risk of skeletal disease in cancer patients. This descriptive systematic review summarizes preclinical and clinical studies dealing with bimodal interactions between pre-existing estrogen deficiency OP and bone metastasis development and provides evidence supporting differences in tumor growth and colonization between healthy and OP status. Few studies evaluated the impact of estrogen deficiency OP on the susceptibility to bone metastases. Therefore, implementing biological knowledge, could help researchers and clinicians to have a better comprehension of the importance of pre- and post-menopausal bone microenvironment and its clinical implications for precision medicine in cancer patients.

Engineered exosomes: A new promise for the management of musculoskeletal diseases

BACKGROUND

Exosomes are nanovesicles actively secreted by potentially all cell types, including tumour cells, with the primary role of extracellular systemic communication mediators, both at autocrine and paracrine levels, at short and long distances. Recently, different studies have used exosomes as a delivery system for a plethora of different molecules, such as drugs, microRNAs and proteins. This has been made possible thanks to the simplicity in exosomes engineering, their great stability and versatility for applications in oncology as well as in regenerative medicine.

SCOPE OF REVIEW

The aim of this review is to provide information on the state-of-the-art and possible applications of engineered exosomes, both for cargo and specific cell-targeting, in different pathologies related to the musculoskeletal system.

MAJOR CONCLUSIONS

The use of exosomes as therapeutic agents is rapidly evolving, different studies explore drug delivery with exosomes using different molecules, showing an enormous potential in various research fields such as oncology and regenerative medicine.

GENERAL SIGNIFICANCE

However, despite the significant progress made by the different studies carried out, currently, the use of exosomes is not a therapeutic reality for the considerable difficulties to overcome.

The Ovariectomized Ewe Model in the Evaluation of Biomaterials for Prosthetic Devices in Spinal Fixation

The effect of surgical ovariectomy on cancellous bone was investigated by comparing mechanical properties and microarchitectural characteristics of the lumbar vertebrae in ovariectomized and sham-operated ewes. Eighteen mongrel ewes, 4±1 years old, were randomly divided into three groups: 6 animals served as a control group (Baseline), 6 were bilaterally ovariectomized (OVX), and the others were used as a sham-operated group (SHAM). OVX and SHAM ewes were euthanized 24 months after surgery; the L5 vertebrae were processed for mechanical and histomorphometric analyses. Maximum load, maximum strength (p<0.0005) and elastic modulus (p <0.005) decreased by about 28% in the OVX group in comparison with the other groups. In the OVX group, vertebral cancellous bone volume, trabecular thickness and trabecular number decreased by about 32% (p<0.0005), 15% (p=0.001) and 20% (p=0.019), respectively. An overall decrease in the bone turnover rate of the OVX group was registered in terms of bone formation rate (p= 0.007) and activation frequency (p<0.0005). The variations observed in cancellous bone mechanics and histomorphometry would suggest the development of an osteopenic state in ewe vertebrae at 24 months. Such findings may be useful for future experimental investigations on biomaterials and prosthetic devices to be implanted in the osteopenic spine.

A Resorbable Biomaterial Shaped as a Tubular Chamber and Containing Stem Cells: A Pilot Study on Artificial Bone Regeneration

In a previous study, we showed how healing of non-union defects in rabbit radii can be achieved by means of a tubular resorbable chamber, in comparison with untreated defects. In the present study, we placed bone marrow stem cells inside the chamber. Bone marrow was obtained by percutaneous aspiration from the iliac crest in 9 adult New Zealand rabbits. Stem cells were separated by the centrifugation technique. In the same animals, a defect of 10 mm was created in both radii. On the left side, the defect was treated with the poly-DL-Lactide chamber, in which a suspension of autologous cells was injected; on the right side, only autologous cells were used. Radiological and histomorphometric data were compared within this study as well as with the results of our previous study. At 3, 6 and 9 months, there was no healing on the right side. On the left side, progressive bone formation with reunion of the stumps was observed in the chamber. We conclude that stem cells can accelerate bone healing when contained in the tubular chamber.

Evaluation of Systemic Metal Diffusion after Spinal Pedicular Fixation with Titanium Alloy and Stainless Steel System: A 36-month Experimental Study in Sheep

It is known that titanium alloys cause more extensive local metallosis due to fretting corrosion than stainless steel implants.

The aim of the present study was to investigate possible systemic metal releases (Ti, Al, V, Cr, Ni) in sheep where L4–L5 were implanted with titanium alloy (Ti6Al4V, ASTM F 136) and stainless steel (AISI 316 L). 16 sheep were used: 8 were implanted with Ti6Al4V and 8 with stainless steel. At 6, 12, 24 and 36 months, the following examinations were performed: histology, atomic absorption spectrophotometry (AAS) and scanning electron microscopy (SEM), on liver, lung, kidney, brain, spleen and lumbo-aortic lymph nodes. Hair, urine and arteria blood samples were also analysed by AAS before implantation and at sacrifices. A histologic and ultrastructural study was performed on peri-implant tissues, too. Particular attention was paid to avoid contamination from dissection instruments or use of containers. In basal and in samples at 6 and 12 months, no metals were found in blood, urine, hair or other target tissues of the animals implanted with either Ti6Al4V or stainless steel. Regarding Al, V, Co and Ni, negative results in all tissues and body fluids were obtained also at 24 and 36 months. On the contrary, Ti traces were found in lumbo-aortic lymph nodes and lungs of one sheep only (10 and 30 ng/g, respectively) at 24 months. At 36 months, a systemic diffusion of Ti was observed in all tissues of both sheep instrumented with Ti6AI4V (2-16.5 ng/g), except for body fluids and hair.

Metal research in target tissues by light and SEM micro-probe analysis provided negative results. Current data suggest that the amount of Ti found in organs after stable pedicular fixation is extremely low and not biologically available. This observation would lead us to exclude the hypothesis of any toxic reaction and such a release seems to be due to the passive diffusion through lymphatic fluids. Additional studies are needed to confirm if this long-term release of Ti particles might cause tissue damage.

Tibial Implants: Biomechanical and Histomorphometric Studies of Hydroxyapatite-Coated and Uncoated Stainless Steel and Titanium Screws in Long-Term Ovariectomized Sheep

This study was designed to evaluate osteointegration of HA-coated and uncoated titanium and stainless steel screws in the cortical bone of long-term (24 months) ovariectomized sheep (OVX group), in comparison with Sham-aged sheep (control group). The screws were tested biomechanically (extraction torque) and histomorphometrically (affinity index: Al) 12 weeks after their implantation in tibial diaphyses. Tibial cortical bone parameters showed significant differences between the groups, showing a reduction of the selected parameters in the OVX group. ANOVA showed significant effects for both material and ovariectomy factors on obtained extraction torque (material: F=159.26, p < 0.0005; ovariectomy: F=20.04, p < 0.0005) and Al data (material: F=8.04, p < 0.001; ovariectomy: F=7.17, p < 0.05). In both groups the extraction torque for coated screws of both materials was significantly higher than for uncoated screws, and uncoated titanium had a better extraction torque than uncoated stainless steel. In the OVX group, the HA-coated stainless steel and titanium Al data were significantly higher than uncoated Al data. In conclusion, the biomechanical and histomorphological results obtained suggest employing HA-coated screws in the presence of osteopenic cortical bone.

Comparison among Three Different Biocoatings for Orthopaedic Prostheses. An Experimental Animal Study

One-hundred-eighty cylindrical monocortical titanium implants, 4mm diameter and 12mm long, with three different coatings: fluorohydroxyapatite (group A), hydroxyapatite (group B), and titanium oxide (group C), all applied by vacuum plasma spray were bilaterally, randomly implanted into the femurs and tibiae of twelve adult mongrel sheep. The sheep were divided into four groups (1, 2, 3 and 4) numbering three sheep each. Sheep of groups 1, 2, 3 and 4 were euthanized at two weeks, one month, three and nine months after implantation, respectively. Biomechanical and histomorphological analysis were performed. Extraction torque increased over time in all groups until the nine months period. At all the studied periods, the bone-implant contact was higher in Groups A and B compared to Group C. However, only at nine months did this difference reach statistical significance (p<0.005 comparing Groups A and B to C). The results of this study show that all the three coatings could be recommended for clinical applications.

Biomaterials in Spinal Fixation. An Experimental Animal Study to Improve the Performance

Different pedicle screws were biomechanically and morphologically studied and compared through the use of an animal model to determine their efficacy and resistance in spinal fixation. The principal objective was to compare biomechanical and histomorphological aspects of HA-coated screws to uncoated ones.

Fourty-eight cylindrical transpedicular self-tapping screws divided into three groups of sixteen each were employed; Group A: stainless steel screws; Group B: titanium screws; Group C: HA-coated titanium screws. The screws were implanted bilaterally and randomly into the L3, L4, and L5 pedicles of eight adult mongrel sheep. The final insertion torque was measured in all the implants. After one and four months, upon euthanization, four samples per group were extracted from the surrounding bone and the screw extraction torque was measured. The remaining samples were examined and processed for histological and histomorphological evaluations.

No differences were observed at one month among the extraction torque of the three groups. After four months the only significance between insertion and extraction values was for the HA group, i.e. p=0.001. Comparing the extraction torque values of the three groups after four months of healing, the HA-coated group showed a greater than twofold increase (p<0.0005). No differences were observed at one month among the percentages of bone-implant contact in the three groups. After four months the percentage was significant only for the C group (p<0.0005). At four months a correlation was found between the morphological and the biomechanical data of group C (p<0.0005).

The use of hydroxyapatite-coated screws could act as an effective method to improve the bone-implant interface, thus obtaining a strong fixation of the implant independently of the arthrodesis achieved with bone graft.

The Ovariectomised Sheep as a Model for Testing Biomaterials and Prosthetic Devices in Osteopenic Bone: A Preliminary Study on Iliac Crest Biopsies

A histomorphometric and ultrastructural evaluation on sheep iliac bone was performed. Six sheep were ovariectomised (OVX Group) and 6 were left intact (Sham-aged, Control Group). An iliac crest biopsy was performed randomly in 6 animals at the beginning of the study, then, in all the animals, after 12 and 24 months. A significant decrease in trabecular bone volume, trabecular thickness (p<0.0005) and cell volume (p<0.005) was observed in OVX animals. A modest decrease in trabecular number and osteoid thickness together with an increase in trabecular separation were observed in OVX animals at 12 and 24 months. The osteoid volume showed a significant difference (p<0.05) between the groups. In OVX animals, at 12 months, Scanning Electron Microscopy revealed an enlargement of the trabecular space and a progressive replacement of bone matrix with adipose tissue. These signs were accentuated at 24 months.

In conclusion, OVX sheep showed a loss of trabecular bone starting at 12 months after ovariectomy. The developed osteopenic state may be considered as a useful tool when doing research on biomaterial osteointegration. (Int J Artif Organs 2000; 23: 275–81)

In Vitro and in Vivo Assessment of Bone-Implant Interface: A Comparative Study

The present in vitro and in vivo comparison of three bioactive (HA, AP40, RKKP) and three bioinert (Ti6-Al4-V, Al2O3, ZrO2) materials was undertaken to identify which of them provide(s) the most suitable coating for prostheses implanted in patients with altered metabolic status.

The experimental design included in vitro tests with human osteoblasts and morphological observations by scanning electron microscopy. For the in vivo evaluation, the materials were implanted in the femoral condyle of ovariectomised and intact female rats, and two months after surgery an X-ray microanalytical study was performed.

The in vitro study showed good biocompatibility with all materials. Microanalysis evidenced a similar behaviour with all materials except the two biological glasses. The differences in Ca and P content observed between intact and ovariectomised rats can be explained by the intrinsic capability of biological glasses to undergo surface modifications in the presence of alterations of the bone metabolism. Thus, their use seems to be indicated in recipients with osteoporotic pathologies.

Hemoperfusion with a New Anion Exchange Resin Corrects the Metabolic Alkalosis in Pyloric Stenosis: An Experimental Demonstration

An experimental model of hypertrophic pyloric stenosis was made by suture of the pyloric wall and gastrostomy in 10 rabbits under general anesthesia. Blood sampling indicated severe alkalosis and hypochloremia 3h 30 min after surgery. To correct the derangement, we tested an ion exchange resin (Dowex SAR), coated with a methacrylic hydrogel. A cartridge containing 18 g of this resin was inserted in an extracorporeal circuit. This chloride charged resin achieved uptake of HCO−3 ions, and elution of CI− ions. The electrolytic balance was fully restored after 10 min of treatment.

Atomic Absorption Spectrophotometry (AAS) for the Evaluation of Metallosis in Prostheses and Artificial Organs: A New Approach

To study the presence of metals in body fluids and tissues after implantation of metallic biomaterials and possible related diseases, a new approach in Atomic Absorption Spectrophotometry (AAS) was developed. This technique was compared to three traditional methods: mineralisation with acid digestion (method A) also known as “wet method”, dry ashing (with or without oxygen) (method B); classic Kjeldaal (method C). The new approach (method D) modifies the mineralisation phase and the instrument operating instructions. Al, Na, Cr, K, Ni, Co, Ti, Fe, Hg, Pb, V, Sb and Cu levels were tested with the four methods on bone, muscle, cartilage, skin, brain, lymph nodes, blood, urine, and hair. Test results were checked by the addition method. Results demonstrated a significantly higher percentage of Al, Cr, Ni, Ti and Hg recovery with the new approach. The advantages of method D are no residue, no redox reaction, insignificant loss of analytes and enhanced sensitivity (at ppb level vs ppm of the other methods). This approach should be considered especially when testing heavy metals and complex matrices. Its disadvantages are that it is more time consuming and requires the presence of an operator.

Biological and Synthetic Conduits in Peripheral Nerve Repair: A Comparative Experimental Study

Two different types of conduits, one biological, obtained with homologous glutaraldehyde preserved vein segments and the other synthetic bioabsorbable, made with Poly [L-lactide-co-6-caprolactone], were evaluated as guides for nerve repair in alternative to autologous grafts in an experimental animal model. Under general anesthetic, the ischiatic nerve of a number Wistar rats was transected to create a 1 cm gap, which was then repaired by means of the conduits or autologous grafts. Controls were performed at 1, 3 and 6 months; nerve regeneration was effective with both conduits, but the count of myelinated axons showed a significant difference between the synthetic and biological tubes (p<0.001). The Poly [L-lactide-co-6-caprolactone] guide was still intact 30 days after implant; progressive signs of degradation were present at 90 and 180 days. These results show that the synthetic conduits are better than those obtained with preserved vein segments and might be considered in alternative to autologous grafts in peripheral nerve reconstruction

pO2 Measurement in an Experimental Model of Patellar Tendon Autograft Pro-Anterior Cruciate Ligament

Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of the patellar tendon, ten enter this study. The purpose was to find a possible relationship between tissue pO2 and healing processes considering also the biomechanical and histomorphological aspects of the grafts. Four of them were sacrificed under general anaesthesia after 6 months, and six after 1 year in order to perform tissue pO2 measurement and an analysis of microvessel density on specimens of the normal ACL and the graft. Our data showed higher pO2 values of the autografts after 6 months. After 1 year the data was comparable to those of native ACL. This was confirmed by a microvessel count of the histological specimens and the data was in relationship to biomechanical and histomorphological analysis. Tissue pO2 can be observed and recorded in “in vivo” ACL, and patellar tendon used as graft, with no injury to their integrity. The monitoring system might be considered as an experimental tool for indirect controls of the anterior cruciate substitutes.

Biopolymeric Modification of Superoxide Dismutase (mPEG-SOD) to Prevent Muscular Ischemia-Reperfusion Damage

The efficacy of preventing ischemia-reperfusion damage by employing native or modified (mPEG-SOD) superoxide dismutase in an experimental animal model of acute ischemia of the left hindlimb was tested. Four hours and thirty minutes complete warm ischemia was induced in the left hindlimb of 43 Wistar rats, by clamping the femoral artery and monitoring its efficacy with Laser Doppler flowmetry. After ten days, a significative difference (p=0.004) of the survival leg rate was found in the group treated with mPEG-SOD (86.6%) compared with the control group (30%). Histomorphological and ultrastructural analysis were performed at different time intervals confirming what the clinical course had already pointed out. These results show that SOD in its modified form, despite the lower dosage, can provide good protection against ischemia/reperfusion injury of muscles.

Influence of Membrane Oxygenators on the Pulsatile flow in Extracorporeal Circuits: An Experimental Analysis

An experimental analysis was carried out to evaluate the effects induced by two typical extracorporeal circuits on the pressure and flow generated by a roller pump with a pulsatile module. The hydraulic behaviour of the patient was simulated by means of a mechanical mock-up system consisting of a few lumped parameters reproducing the physiologic vascular impedance. Pressure and flow tracings were acquired at different locations along the circuit using an automatic data acquisition system. Nine test conditions with different pulse frequency and systolic time values were examined using a mean volumetric flow rate of approximately 4 l/min. A complete analysis of the results obtained in terms of pressure drops and inflow-outflow differences across the components of the arterial line, as well as the calculation of the hydraulic pulsatile power along the circuit, allowed us to assess the influence of the various components upon the pulsatility. The results indicated that the membrane oxygenators tested slightly affect the pulsatility of the flow and the pressure; on the contrary the arterial pipe line is responsible for large damping and head losses. To optimize the use of pulsatile flow for cardiopulmonary bypass it is necessary to reduce the length of the arterial pipe lines thus integrating the circuit as much as possible.

Biomaterials for Orthopedic Surgery in Osteoporotic Bone: A Comparative Study in Osteopenic Rats

To evaluate orthopedic devices in pathological bone, an experimental study was performed by implanting Titanium (Ti) and Hydroxyapatite (HA) rods in normal and osteopenic bone. Twenty-four rats were used: 12 were left intact (Control: C) while the other 12 were ovariectomized (OVX). After 4 months all the animals were submitted to the implant of Ti or HA in the left femoral condyle (Ti-C, HA-C, Ti-OVX, HA-OVX). Two months later the animals were sacrificed for histomorphometric, ultrastructural and microanalytic studies. Our results show a significant difference between the Affinity Index (A.I.) of HA-C and Ti-C (77.0 ± 7.4 vs 61.2 ± 9.7) (p < 0.05). No significant differences were observed between the osteointegration of Ti-C and Ti-OVX (61.2 ± 9.7 vs 48.2 ± 6.7). Significant differences also exist between the osteointegration of HA-C and HA-OVX (77.0 ± 7.4 vs 57.6 ± 11.5) (p < 0.01). Microanalysis shows some modifications in Sulphur (S) concentration at the bone/biomaterial interface of the Ti-OVX group. Therefore our results confirmed the importance of biomaterials characteristics and of bone quality in osteointegration processes.

Resorbable Device for Fracture Fixation: In Vivo Degradation and Mechanical Behaviour

The availability of a high molecular weight poly(L-lactide), with supposed good mechanical properties, encouraged us to carry out an in vivo experimental study to evaluate the degradation rate and accompanying loss of strength during interaction with bone. Small cylindrical PLLA rods were manufactured by compression moulding. Thirty-six male New Zealand rabbits (b.w. 3 kg), randomly divided into six groups of six animals each, were submitted to implantation of the rods under general anaesthesia (0 3x7 mm rods in the lateral condylic region of the right femur and 0 3x50 mm rods in the intracondylic channel of the left femur). The animals were then sacrificed at the end of each experimental time (4, 8, 12, 24, 52, 64 weeks), hence the femurs were explanted. Histology showed no inflammatory cells with fragmentation or resorption of bone trabeculae. Mechanical studies showed a decrease in mechanical properties and flexional stiffness, and the absence of evident material resorption. Finally, the properties of this newly developed resorbable device, when confirmed, seem to justify future clinical introduction of this synthetic material.

A New Chemical Etching Process to Improve Endosseous Implant Osseointegration: In Vitro Evaluation on Human Osteoblast-Like Cells

The development of novel mechanical and chemical surface modification treatments to improve the osteointegration properties of osseointegrated dental implants is nowadays a topic of great applicative interest. The aim of the present study was to analyse the role of surface topography and chemistry of four different surface treatments on titanium by an in vitro human osteosarcoma immortalised cell line model (MG63). The surface treatments considered were (a) machined titanium, (b) chemical etched on machined titanium, (c) sandblasted titanium and (d) chemical etching on sandblasted titanium.

Chemical and physical surface properties were investigated by Scanning Electron Microscopy, Thin Film-X ray Diffraction and by Laser Profilometry. The in vitro biological response was characterised using the MG63 cell line by elution cytotoxicity tests, cell morphology, adhesion, proliferation activity, alkaline phosphatase activity and total DNA content in order to show a relationship between osteoblast response and surface features.

Chemical and physical characterisation showed that the considered treatments differently modify the surface morphology in the micro and sub-micrometric scale. Although some differences in alkaline phosphatase activity were observed in the biological characterisation, depending on the specific material's surface finishing, the results showed that cells were well responsive on all the tested materials and grew and differentiated with similar proliferation rate.

Osseointegration of Sandblasted or Anodised Hydrothermally-Treated Titanium Implants: Mechanical, Histomorphometric and Bone Hardness Measurements

The improvement of the implant-bone interface is still an open problem in the long-term mechanical stability of cementless fixed implants. Mechanical, histomorphometric and bone hardness measurements were performed in sheep femoral cortical bone implants at 8 and 12 weeks from surgery to compare in vivo the osseointegration of titanium screws (Ø 3.5 mm × 7 mm length) with two different surface treatments: sandblasting with 70–100 μm HA followed by acid etching with HNO3 (Group A) and Ca-P anodization followed by a hydrothermal treatment (Group B). No significant differences were found for maximum push-out force and interfacial strength between groups at both experimental times. No significant difference was observed for Bone Ingrowth between groups at both experimental times, while the Affinity Index of Group B was significantly higher (7.5%, p<0.05) and lower (10.2%, p<0.05) than that of Group A at 8 and 12 weeks, respectively. Finally, a significant increase in bone microhardness measured within 200 μm from the interface and inside the thread depth of Group A was observed between the two experimental times (p<0.05). In conclusion, present findings show that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as current tested treatments which enhance bone interlocking and mineralization.

Tailoring Biomaterial Compatibility: In Vivo Tissue Response versus in Vitro Cell Behavior

Biocompatibility relies essentially on surface phenomena, represented by cell-cell, cell-material and material (polymer)-protein interactions. An in vivo and in vitro experimental investigation was carried out on the biomaterials of two different classes with a good potential for in situ utilisation. Non-resorbable (Polypyrrole, Polyaniline, Polyimide) and resorbable (PLLA-PDXO-PLLA) materials for tissue engineering were studied for their overall tissue tolerance and cellular interactions. These non-resorbable polymers conceived for biosensor applications and implantable drug-delivery systems are intrinsically conductive. The PLLA-PDXO-PLLA triblock copolymer showed interesting tensile properties for bone and cartilage tissue engineering due to the presence of 1,5-dioxepan-2-one. In vitro and in vivo parallel studies showed an interesting correspondence: a) the cells in contact with the resorbable material that appeared to be capable of migratory-regenerative aspects in vitro exhibited good compatibility in vivo; whereas b) the non-resorbable materials, which are designed to remain in situ in vivo, were seen to have the potential to represent an adverse factor (inflammation, fibrotic reactions) that correlated with some aspects of cell behaviour in vitro.

Shock Wave Therapy as an Innovative Technology in Skeletal Disorders: Study on Transmembrane Current in Stimulated Osteoblast-Like Cells

Extracorporeal shock wave treatment (ESWT) is successfully used in various musculoskeletal disorders and pathologies. Despite the increasing use of this kind of therapy, some aspects of its mechanism of action are still unclear. In vitro bone cell behavior under ESWT were previously investigated by the present author and MG63 osteoblast-like cells showed an enhancement in proliferation and in the osteoblast differentiation after therapy with a low-energy flux density. The aim of the present study was to evaluate the effect of ESWT on the permeabilization of cell membrane. We characterized physiological changes in the MG63 associated with ESWT generated by an ESW device and patch clamp recording was performed to study ion channels. Experiments were carried out using the whole-cell recording configuration of the patch-clamp technique and the ionic current measurements were performed on cell samples of ESW treated and control groups. The patch-clamp technique showed the effect of ESWT on the amplitude of transmembrane currents. The treatment with ESW enhanced the transmembrane current as well the voltage dependence of Ca-activated and K channels that mediate these currents: the differences between treated cells and control at 80mV were over 1000 pA (P<0.05). These modifications of ion channels activity positively influence cell proliferation (MTT test, P<0.0001) without interfering with the normal synthesis activity of stimulated osteoblasts.

Cell Dynamics in the Correct Control of Bone Metabolism Using Natural Treatments

The present study was undertaken in order to assess the efficacy of a commercial product containing calcium and silicon (Osteosil-Calcium®) on cell metabolism. MG-63 osteblast-like cells were cultured in the presence of three different drug concentrations (10, 5 and 2.5 μg/mL). Either serum-free culture and standard culture with serum were investigated. Morpho-functional tests (MTT and ALP), scanning electron microscopy (SEM), microanalysis (EDAX) and time-lapse video microscopy were performed. Cell actin cytoskeletal modification with fluorescence phalloidin staining was also tested. Our data show the in vitro functional efficacy of Osteosil-Calcium® on MG63 cell viability and ALP production. This study demonstrates its positive effect on the metabolism of the single cell and suggests wider uses of this drug in health protection and or in Regenerative Medicine therapies which are currently applied to the elderly

In Vitro Evaluation of Bio-Functional Performances of Ghimas Titanium Implants

Titanium is the most widely used material for dental implants. The natural formation, in presence of oxygen, of different oxide films (passivation films) is correlated to titanium implant biocompatibility, resistance to corrosion and is responsible for implant bacteriostatic action. Surface roughness is another surface property of Ti-implants that, affecting implant-to-bone contact, improves integration. In the present study data concerning composition, surface roughness and biocompatibility of Ghimas implants and mini-implants undergoing sandblasting with Calcium Magnesium Carbonate (CaMg(CO3)2) are reported. AFM, SEM/EDX, XRD analyses and morphofunctional tests (MTT and ALP) were performed. Cell actin cytoskeletal modification (fluorescence phalloidin staining) was also observed with confocal laser microscopy (CLSM). Data related to surface geometry and chemical properties, associated with evidence of high purity of all the tested materials (XRD and EDX), highlighted the elevated biocompatibility of tested implants and mini-implants. CLSM investigation confirmed osteoblast features of an active cell behavior able to fit cell to chemico-mechanical stimuli present at the bone/implant interface and suggests an effective implant/alveolar bone integration in vivo.

In Vitro Biocompatibility of Titanium Oxide for Prosthetic Devices Nanostructured by Low Pressure Metal-Organic Chemical Vapor Deposition

Metal-Organic Chemical Vapor Deposition (MOCVD) has recently been proposed to coat orthopedic and dental prostheses with metal nanostructured oxide films through the decomposition of oxygenated compounds (single-source precursors) or the reaction of oxygen-free metal compounds with oxygenating agents. The present study was carried out to assess the in vitro biocompatibility in terms of cell proliferation and activation, of commercially pure Ti (control material: TI/MA) coated with nanostructured TiO2 film by MOCVD (Ti/MOCVD) using osteoblast-like cell cultures (MG-63). Evaluations were performed at 3, 7 and 14 days. Cell proliferation showed a similar trend for Ti/MA and Ti/MOCVD compared to polystyrene; cell number increased with time from seeding to day 7 (p < 0.005), and then decreased progressively until day 14 (ranging from −14% to −47%). The ALP level and OC production showed no significant differences between Ti/MOCVD and Ti/MA at each experimental time. Significantly higher ALP levels were found in Ti/MA at 3 days and in Ti/MOCVD at 7 and 14 days when compared to the polystyrene group. OC production decreased over time and the highest values were observed at 3 days, when it was significantly higher in the Ti/MA than in the polystyrene group (50%, p < 0.05). CICP synthesis was positively affected by the presence of Ti/MOCVD and was higher in Ti/MOCVD than in the polystyrene group. No significant differences were found between Ti/MOCVD and Ti/MA in terms of IL-6 and TGF-ß1 synthesis at any experimental time. In conclusion, the current findings demonstrate that the nanostructured TiO2 coating positively affects the osteoblast-like cell behavior in terms of cell proliferation and activity, thus confirming its high level of in vitro biocompatibility in accordance with expectations.

Biomaterials in Orthopedic Surgery: Effects of a Nickel-Reduced Stainless Steel on in Vitro Proliferation and Activation of Human Osteoblasts

A new austenitic stainless steel compound, P558, has been widely recognized to have good mechanical properties, excellent potential for corrosion resistance and negligible nickel ion release, making it a promising substitute for more expensive metallic prostheses with limited machinable features. The effect of P558 was studied in vitro and human osteoblast- like cells (MG63) were cultured directly on P558, Ti6Al4V alloy (Ti), and polystyrene (Control) for 72 hours. Osteoblast functions were evaluated by assaying cell proliferation and synthetic activity after 1.25(OH)2D3 stimulation. Results demonstrated that growth of MG63 on P558 was not negatively affected when compared to the Ti and Control groups and showed no alteration in the production of ALP, NO and PICP. Moreover, IL-6 was lower, whereas OC and TGFbeta1 were significantly higher. SEM images revealed that cells proliferated and differentiated on P558 without any alteration in their morphology. The current findings have demonstrated that P558 promotes osteoblast proliferation, activation and differentiation without negative effects and, thus, its good biocompatibility when used for orthopedic application.

Vascular Endothelial Growth Factor (Vegf) and Other Common Tissue Prognostic Indicators in Breast Cancer: A Case-Control Study

VEGF is a specific mitogen and survival factor for endothelial cells and a key promoter of angiogenesis in physiological and pathological conditions. Nevertheless, VEGF tissue evaluation in cancer patients as a prognostic factor compared to the conventional histological and biological parameters is still controversial. In this case-control study, tissue VEGF was retrospectively determined by immunohistochemistry and related to T, N, ER, PgR, c-erbB-2, p53, MIB-1 and cyclin D1 in 129 breast cancer patients. Seventy-four of these patients had developed distant metastases postoperatively. The remaining 55 patients had remained disease-free >10 years after surgery. In 17 (13%) of the 129 patients (six with distant metastases and eleven disease-free) tissue and plasma VEGF were concomitantly evaluated. In univariate analysis no significant differences in VEGF and tumor size were found between metastatic and disease-free patients, whereas there were significant differences in N, ER, PgR, c-erbB-2, p53, MIB-1 and cyclin D1 (p ranging from 0.001 to 0.0001). In multivariate analysis VEGF showed less significance than N, ER, c-erbB-2, MIB-1 and cyclin D1 (p=0.012, p=0.007, p=0.005, p=0.005, p=0.002 and p=0.001, respectively). VEGF was a significant unfavorable prognostic indicator only in the N+ subset (p=0.015), while ER (p=0.05 and p=0.021) and MIB-1 (p=0.031 and p=0.022) were significant in both the N+ and N– subgroups. In multivariate analysis in the 74 metastatic cases VEGF did not show any significance in relation to disease-free interval and overall survival from the time of mastectomy and from the time of relapse, whereas N and PgR did (p ranging from 0.018 to 0.001). In conclusion, tissue VEGF does not seem a suitable candidate to replace conventional histological and other common biological prognostic factors in breast cancer.

Biomedical Coatings to Improve the Tissue-Biomaterial Interface

One of the most important factors determining the degree of tissue interaction of an implanted device is the property of its surface. Thus, great importance is given to chemical and morphological characteristics of biomaterial surfaces to improve biocompatibility, cell migration, proliferation and differentiation, mechanical stability and endogenous tissue ingrowth.

In order to obtain new and healing stimulating properties, it is possible to apply a coating or more generally a surface treatment to the surface of a prosthetic device. One of the most versatile methods for coating is thermal spray technology. This paper considers the principle of thermal spray processes and their application in the biomedical field, namely the coatings used for orthopedic prostheses and dental implants. Among thermal spray processes, plasma spray as well as High Velocity Oxygen Fuel (HVOF) processes will be particularly considered and their most important aspects will be illustrated.

Sandblasted Titanium Osteointegration in Young, Aged and Ovariectomized Sheep

To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium (Ti/SA) implants, the osteointegration of Ti/SA rods was studied in the cortical and trabecular bone of 5 young, 5 aged and 5 ovariectomized (OVX) sheep.

The characterization of the host bone by transiliac biopsies of the iliac crest showed a progressive rarefaction of trabecular bone in aged and OVX animals when compared to young ones. A significant reduction, both in cortical and trabecular bone, of the osteointegration rate of Ti/SA rods in the presence of estrogen deficiency compared to young animals was observed, while only a minor reduction was observed in aged animals. These results were confirmed by the pushout test in cortical bone.

Bone quality affected the biological response of bone to Ti/SA implants in both trabecular and cortical bone; consequently, strategies to maximize the bone osteogenic properties of osteoporotic patients should be adopted.

In vitro Models to Test Orthopedic Biomaterials in View of Their Clinical Application in Osteoporotic Bone

The development of in vitro cell cultures, in association with in vivo experimentation, greatly improved the characterization of biomaterials for orthopedic devices before their clinical use. In recent years an increasing interest has arisen in the use of both pathological osteoblast cultures and animal models to perform in vitro and in vivo tests on biomaterial behavior. A growing number of prostheses, in fact, are implanted in osteoporotic patients, due to the increasing age of the population. Moreover, the presence of osteoporosis may affect bone-biomaterial osteointegration in these patients.

The present paper is a literature review and, after a short description of in vitro studies for characterization of osteoblasts derived from osteoporotic bone, the results of in vitro studies on biomaterial biocompatibility and osteointegration rate in the presence of osteoporotic bone derived osteoblast cultures are reported. Pathological cell culture models are able to demonstrate the different behavior of osteoblasts in response to biomaterials, when comparing normal and pathological conditions.

Natural and Synthetic Polyesters for Musculoskeletal Tissue Repair: Experimental in Vitro and in Vivo Evaluations

Two natural Biopol™ polyesters, containing 8% (D400G) and 12% (D600G) of hydroxyvalerate component, and a synthetic polyester based on 1,4 cyclohexanediol [Poly(cyclohexyl-sebacate) - PCS] were studied to investigate their in vitro and in vivo behavior for application in musculoskeletal tissue repair. The polyesters were placed in direct contact with L929 fibroblasts and cell proliferation (WST-1), cytotoxic effect (LDH), synthetic activity (total proteins) and cytokine production (IL-1β, IL-6, TNFα) were assessed after an incubation period of 72 hours and 7 days. Then, 12 Sprague-Dawley rats underwent dorsal subcutaneous implants of tested polyesters under general anesthesia. After 1 and 4 weeks from surgery, the animals were pharmacologically euthanized and the implants retrieved with surrounding tissue for histologic and histomorphometric investigations. In vitro results showed that D600G behaved a little worse in comparison to other tested polyesters in terms of cell proliferation and TNFα at 7 days. PCS presented the lowest total protein value at 7 days. In vivo results indicated that PCS implants produced a higher (p < 0.01) extent of inflammatory tissue in comparison to D600G at 1 week and to D400G at 4 weeks, and the lowest vascular densities at both experimental times. D400G seems to be the most suitable material for biomedical application when tested in fibroblast cultures and in the subcutaneous tissue of rats.

Biomaterials as bone graft substitutes for spine surgery: from preclinical results to clinical study

Vertebral fusion is performed in order to stabilize the spine in the presence of degenerative, traumatic or oncological pathologies that alter its stability. The autologous bone, harvested from the patient’s iliac crest or from the lamina during surgery, is still considered the “gold standard” for spine fusion due to its osteogenic, osteoinductive and osteoconductive properties. However, several biological and synthetic bone substitutes have been introduced as alternatives for regenerating bone tissue. We have studied in particular the use of ceramic biomaterials prepared from hydroxypatite (HA), starting from in vitro analysis, through an in vivo study on ovine animal model and a post-market surveillance analysis, to finally design and perform a clinical study, which is ongoing in our Department. In the first step, HA-derived biomaterials were tested in vitro in the presence of bone marrow-derived human mesenchymal stem cells (hMSCs) and evaluated for their ability to activate precursor cells. In the second step, the biomimetic bone graft substitute SintLife® putty (MgHA) was evaluated in vivo. A posterolateral fusion procedure was applied on 18 sheep, where a fusion level was treated with MgHA, while the other level was treated with autologous bone. Microtomography and histological/histomorphometric analysis were performed six months of after surgery. In the third step, we reported the results of a post-market surveillance study conducted on 4 independent cohorts of patients (total 115 patients), in which HA-derived biomaterials were used as bone graft substitutes or extenders. Finally, a clinical study has been designed and approved by the Ethics Committee of our Institute and is currently ongoing. This study aims to evaluate the efficacy of the ceramic biomaterial SintLife® putty for bone replacement in patients treated by posterolateral fusion for degenerative spine disorders. HA biomaterials were effective in promoting the in vitro growth of hMSCs and their osteogenic differentiation. In the animal model, SintLife® putty has been effective in generating neo-formed bone tissue with morphological and structural features similar to those of the pre-existing bone. The post-market surveillance analysis has not reported any intra-operative nor early or late post-operative adverse events. Seven patients are currently recruited for the clinical trial designed to evaluate Sintlife efficacy for spine fusion (FU range: 1-7 months). No adverse events have been recorded. The first CT analysis performed at 6 months FU showed a good spine fusion. The study is ongoing. Our results, obtained from in vitro, preclinical and clinical studies, suggest that biomaterials derived from hydroxyapatite could be a valid alternative to autologous bone graft for vertebral fusion. This would potentially avoid or reduce the need of autologous bone harvesting and therefore, the risk of drawback-related side effects.

Lipid-lowering effect of bergamot polyphenolic fraction: role of pancreatic cholesterol ester hydrolase

Bergamot polyphenolic fraction (BPF) has been shown to positively modulate several mechanisms involved in metabolic syndrome, suggesting its use in therapy. In particular, it is able to induce a significant amelioration of serum lipid profile in hyperlipemic patients at different levels. The purpose of our study was to investigate the effect of BPF on cholesterol absorption physiologically mediated by pancreatic cholesterol ester hydrolase (pCEH). An in vitro activity assay was performed to study the effect of BPF on pCEH, whereas the rate of cholesterol absorption was evaluated through in vivo studies. In particular, male, Sprague-Dawley rats (200–225 g) were fed either normal chow or chow supplemented with 0.5% cholic acid, 5.5% peanut oil, and varying amounts of cholesterol (0 to 1.5%). BPF (10 mg/Kg) was daily administrated by means of a gastric gavage to animals fed with lipid supplemented diet for 4 weeks and, at the end of the study, plasma lipids and liver cholesteryl esters were measured in all experimental groups. Our results show that BPF was able to inhibit pCEH activity and this effect was confirmed, in vivo, via detection of lymphatic cholesteryl ester in rats fed with a cholesterol-rich diet. This evidence clarifies a further mechanism responsible for the hypolipemic properties of BPF previously observed in humans, confirming its beneficial effect in the therapy of hypercholesterolemia and in the treatment of metabolic syndrome.

Spontaneous osteoclastogenesis: Hypothesis for gender-unrelated osteoporosis screening and diagnosis

Women are at greater risk of developing osteoporosis (OP). However, in the past few years it has become more widely recognized that OP is a significant problem also in men although OP is frequently under-diagnosed and, consequently, under treated in men. Most guidelines, screening and fracture risk evaluation methods as well as pharmacologic agents have been developed for women and then adapted to men. Bone Mineral Density (BMD) measurement by Dual X-ray Absorptiometry (DEXA) is reported as T score and the capability of DEXA to diagnose OP and predict fracture risk is still debated. In addition, the use of female T score references for the diagnosis of OP in men is incorrect for the following reasons: 1) DXA definition was developed just for Caucasian women, 2) men and women display structural differences in terms of bone growth, catabolism and size; 3) aging men have more periosteal apposition, less cortical porosity and endocortical resorption than aging women; and 4) T scores results, both in man and in women, can be affected by the presence of co-morbidities and it is known that in men OP is often secondary. From a biological point of view, OP is mainly due to increased osteoclastic activity leading to an imbalance in bone remodeling that favors resorption. However, some evidence suggests a more complex identity for osteoclasts (OCs) over and above their simple role of 'bone eaters'. In our laboratory, we observed spontaneous OCs formation in vitro in peripheral blood mononuclear cells (PBMC) from OP patients (n.12 female patients and n.6 male patients; DXA T score-2.5 or less). Some researchers demonstrated OCs gender differences in bone resorption activity of female-derived versus male-derived OCs. Indeed, further data from our laboratory also showed gender differences in number of spontaneously differentiated OCs and differentiation time. Therefore, we hypothesized that it would be possible to perform OP screening and diagnosis observing and measuring PBMCs different ability to differentiate spontaneously into OCs in male and female patients. If this hypothesis will be confirmed, it will result in an effective and efficient strategy for OP screening, diagnosis, monitoring and fracture prevention, targeting health service resources on selected patients. However, our hypothesis must be tested in a properly designed clinical trial and several key issues still need to be addressed.

Fresh osteochondral allotransplants: Outcomes, failures and future developments

Osteochondral allografts are used to treat many different conditions as acute traumatic large-sized lesions, degenerative osteoarthritis, osteochondritis dissecans, avascular necrosis or in case of failure of previous procedures particularly in young patients for whom primary prosthesis is not desirable. Fresh allografts present the advantage of having mature viable hyaline cartilage, not causing donor morbidity, allowing the restoration of even large defects in a single surgical session. Conversely, they could account for risks of disease transmission, immunologic reactions, and for limited availability. The present review aimed to analyze published studies of the last decade in which patients received fresh osteochondral allografts by dividing them for knee or ankle regenerative purposes. We wish to report the observed failure rates and particularly to collect any other reported side effect or outcome for identifying major problems and limits linked to the procedure and for delineating possible future researches and approaches. The overall success rates resulted ranging from 5.3% to 48.3% in the ankle at a mean follow up of 3.3 years and from 0% to 85.7% in the knee at a mean follow up of 7.1 years. Among other outcomes, occurrence or progression of arthritis, osteolysis, graft instability, fractures, nonunions, edema and infections were recorded. Overall, the lack of well designed randomized and controlled clinical trials, of immunological determination of the anti-donor antibodies development and of local and systemic biomarkers to detect reaction to the graft seems to be the major drawback. Improvements in these limiting factors might be desirable in order to enhance the clinical scenario of a well-established and successful procedure to give, especially for young patients, a real regeneration of the joint.