James V. Sugai

Vascular Targeted Nanoparticles for Imaging and Treatment of Brain Tumors

Purpose: Development of new therapeutic drug delivery systems is an area of significant research interest. The ability to directly target a therapeutic agent to a tumor site would minimize systemic drug exposure, thus providing the potential for increasing the therapeutic index. Experimental Design: Photodynamic therapy (PDT) involves the uptake of a sensitizer by the cancer cells followed by photoirradiation to activate the sensitizer. PDT using Photofrin has certain disadvantages that include prolonged cutaneous photosensitization. Delivery of nanoparticles encapsulated with photodynamic agent specifically to a tumor site could potentially overcome the drawbacks of systemic therapy. In this study, we have developed a multifunctional polymeric nanoparticle consisting of a surface-localized tumor vasculature targeting F3 peptide and encapsulated PDT and imaging agents. Results: The nanoparticles specifically bound to the surface of MDA-435 cells in vitro and were internalized conferring photosensitivity to the cells. Significant magnetic resonance imaging contrast enhancement was achieved in i.c. rat 9L gliomas following i.v. nanoparticle administration. Serial magnetic resonance imaging was used for determination of pharmacokinetics and distribution of nanoparticles within the tumor. Treatment of glioma-bearing rats with targeted nanoparticles followed by PDT showed a significant improvement in survival rate when compared with animals who received PDT after administration of nontargeted nanoparticles or systemic Photofrin. Conclusions: This study reveals the versatility and efficacy of the multifunctional nanoparticle for the targeted detection and treatment of cancer.

Tissue engineering bone-ligament complexes using fiber-guiding scaffolds

Regeneration of bone-ligament complexes destroyed due to disease or injury is a clinical challenge due to complex topologies and tissue integration required for functional restoration. Attempts to reconstruct soft-hard tissue interfaces have met with limited clinical success. In this investigation, we manufactured biomimetic fiber-guiding scaffolds using solid free-form fabrication methods that custom fit complex anatomical defects to guide functionally-oriented ligamentous fibers in vivo. Compared to traditional, amorphous or random-porous polymeric scaffolds, the use of perpendicularly oriented micro-channels provides better guidance for cellular processes anchoring ligaments between two distinct mineralized structures. These structures withstood biomechanical loading to restore large osseous defects. Cell transplantation using hybrid scaffolding constructs with guidance channels resulted in predictable oriented fiber architecture, greater control of tissue infiltration, and better organization of ligament interface than random scaffold architectures. These findings demonstrate that fiber-guiding scaffolds drive neogenesis of triphasic bone-ligament integration for a variety of clinical scenarios.

Nanofibrous Scaffolds Incorporating PDGF-BB Microspheres Induce Chemokine Expression and Tissue Neogenesis In Vivo

Platelet-derived growth factor (PDGF) exerts multiple cellular effects that stimulate wound repair in multiple tissues. However, a major obstacle for its successful clinical application is the delivery system, which ultimately controls the in vivo release rate of PDGF. Polylactic-co-glycolic acid (PLGA) microspheres (MS) in nanofibrous scaffolds (NFS) have been shown to control the release of rhPDGF-BB in vitro. In order to investigate the effects of rhPDGF-BB release from MS in NFS on gene expression and enhancement of soft tissue engineering, rhPDGF-BB was incorporated into differing molecular weight (MW) polymeric MS. By controlling the MW of the MS over a range of 6.5 KDa–64 KDa, release rates of PDGF can be regulated over periods of weeks to months in vitro. The NFS-MS scaffolds were divided into multiple groups based on MS release characteristics and PDGF concentration ranging from 2.5–25.0 µg and evaluated in vivo in a soft tissue wound repair model in the dorsa of rats. At 3, 7, 14 and 21 days post-implantation, the scaffold implants were harvested followed by assessments of cell penetration, vasculogenesis and tissue neogenesis. Gene expression profiles using cDNA microarrays were performed on the PDGF-releasing NFS. The percentage of tissue invasion into MS-containing NFS at 7 days was higher in the PDGF groups when compared to controls. Blood vessel number in the HMW groups containing either 2.5 or 25 µg PDGF was increased above those of other groups at 7d (p<0.01). Results from cDNA array showed that PDGF strongly enhanced in vivo gene expression of the CXC chemokine family members such as CXCL1, CXCL2 and CXCL5. Thus, sustained release of rhPDGF-BB, controlled by slow-releasing MS associated with the NFS delivery system, enhanced cell migration and angiogenesis in vivo, and may be related to an induced expression of chemokine-related genes. This approach offers a technology to accurately control growth factor release to promote soft tissue engineering in vivo.

Adenovirus Encoding Human Platelet-Derived Growth Factor-B Delivered to Alveolar Bone Defects Exhibits Safety and Biodistribution Profiles Favorable for Clinical Use

Platelet-derived growth factor (PDGF) gene therapy offers promise for tissue engineering of tooth-supporting alveolar bone defects. To date, limited information exists regarding the safety profile and systemic biodistribution of PDGF gene therapy vectors when delivered locally to periodontal osseous defects. The aim of this preclinical study was to determine the safety profile of adenovirus encoding the PDGF-B gene (AdPDGF-B) delivered in a collagen matrix to periodontal lesions. Standardized alveolar bone defects were created in rats, followed by delivery of matrix alone or containing AdPDGF-B at 5.5 x 10(8) or 5.5 x 10(9) plaque-forming units/ml. The regenerative response was confirmed histologically. Gross clinical observations, hematology, and blood chemistries were monitored to evaluate systemic involvement. Bioluminescence and quantitative polymerase chain reaction were used to assess vector biodistribution. No significant histopathological changes were noted during the investigation. Minor alterations in specific hematological and blood chemistries were seen; however, most parameters were within the normal range for all groups. Bioluminescence analysis revealed vector distribution at the axillary lymph nodes during the first 2 weeks with subsequent return to baseline levels. AdPDGF-B was well contained within the localized osseous defect area without viremia or distant organ involvement. These results indicate that AdPDGF-B delivered in a collagen matrix exhibits acceptable safety profiles for possible use in human clinical studies.

Porphyromonas gingivalis oral infection exacerbates the development and severity of collagen-induced arthritis

IntroductionClinical studies suggest a direct influence of periodontal disease (PD) on serum inflammatory markers and disease assessment of patients with established rheumatoid arthritis (RA). However, the influence of PD on arthritis development remains unclear. This investigation was undertaken to determine the contribution of chronic PD to immune activation and development of joint inflammation using the collagen-induced arthritis (CIA) model.MethodsDBA1/J mice orally infected with Porphyromonas gingivalis were administered with collagen II (CII) emulsified in complete Freund’s adjuvant (CFA) or incomplete Freund’s adjuvant (IFA) to induce arthritis. Arthritis development was assessed by visual scoring of paw swelling, caliper measurement of the paws, mRNA expression, paw micro-computed tomography (micro-CT) analysis, histology, and tartrate resistant acid phosphatase for osteoclast detection (TRAP)-positive immunohistochemistry. Serum and reactivated splenocytes were evaluated for cytokine expression.ResultsMice induced for PD and/or arthritis developed periodontal disease, shown by decreased alveolar bone and alteration of mRNA expression in gingival tissues and submandibular lymph nodes compared to vehicle. P. gingivalis oral infection increased paw swelling and osteoclast numbers in mice immunized with CFA/CII. Arthritis incidence and severity were increased by P. gingivalis in mice that received IFA/CII immunizations. Increased synovitis, bone erosions, and osteoclast numbers in the paws were observed following IFA/CII immunizations in mice infected with P gingivalis. Furthermore, cytokine analysis showed a trend toward increased serum Th17/Th1 ratios when P. gingivalis infection was present in mice receiving either CFA/CII or IFA/CII immunizations. Significant cytokine increases induced by P. gingivalis oral infection were mostly associated to Th17-related cytokines of reactivated splenic cells, including IL-1β, IL-6, and IL-22 in the CFA/CII group and IL-1β, tumor necrosis factor-α, transforming growth factor-β, IL-6 and IL-23 in the IFA/CII group.ConclusionsChronic P. gingivalis oral infection prior to arthritis induction increases the immune system activation favoring Th17 cell responses, and ultimately accelerating arthritis development. These results suggest that chronic oral infection may influence RA development mainly through activation of Th17-related pathways.

Gene Expression Dynamics During Bone Healing and Osseointegration

BACKGROUND Understanding the molecular features of bone repair and osseointegration may aid in the development of therapeutics to improve implant outcomes. The purpose of this investigation is to determine the gene expression dynamics during alveolar bone repair and implant osseointegration. METHODS An implant osseointegration preclinical animal model was used whereby maxillary defects were created at the time of oral implant placement, while a tooth extraction socket healing model was established on the contralateral side of each animal. The surrounding tissues in the zone of the healing defects were harvested during regeneration for temporal evaluation using histology, immunohistochemistry, laser capture microdissection, and quantitative reverse transcription-polymerase chain reaction for the identification of a panel of 17 putative genes associated with wound repair. RESULTS In both models, three distinct expression patterns were displayed: 1) genes that are slowly increased during the healing process, such as bone morphogenetic protein 4, runt-related transcription factor 2, and osteocalcin; 2) genes that are upregulated at the early stage of healing and then downregulated at later stages, such as interleukin and chemokine (C-X-C motif) ligands 2 and 5; and 3) genes that are constitutively expressed over time, such as scleraxis. Although some similarities between osseointegration and tooth extraction socket were seen, distinct features developed and triggered a characteristic coordinated expression and orchestration of transcription factors, growth factors, extracellular matrix molecules, and chemokines. CONCLUSIONS Characterization of these events contributes to a better understanding of cooperative molecular dynamics in alveolar bone healing, and highlights potential pathways that could be further explored for the enhancement of osseous regenerative strategies.

Sclerostin antibody stimulates bone regeneration after experimental periodontitis

The reconstruction of large osseous defects due to periodontitis is a challenge in regenerative therapy. Sclerostin, secreted by osteocytes, is a key physiological inhibitor of osteogenesis. Pharmacologic inhibition of sclerostin using sclerostin‐neutralizing monoclonal antibody (Scl‐Ab) thus increases bone formation, bone mass and bone strength in models of osteopenia and fracture repair. This study assessed the therapeutic potential of Scl‐Ab to stimulate alveolar bone regeneration following experimental periodontitis (EP). Ligature‐induced EP was induced in rats to generate localized alveolar bone defects. Following 4 weeks of disease induction, Scl‐Ab (+EP) or vehicle (+/− EP) were systemically delivered, twice weekly for up to 6 wks to determine the ability of Scl‐Ab to regenerate bone around tooth‐supporting osseous defects. 3 and 6 wks after the initiation of Scl‐Ab or vehicle treatment, femur and maxillary jawbones were harvested for histology, histomorphometry, and micro‐computed tomography (micro‐CT) of linear alveolar bone loss (ABL) and volumetric measures of bone support, including bone volume fraction (BVF) and tissue mineral density (TMD). Serum was analyzed to examine bone turnover markers during disease and regenerative therapy. Vehicle + EP animals exhibited maxillary bone loss (BVF, TMD and ABL) at ligature removal and thereafter. 6 weeks of Scl‐Ab significantly improved maxillary bone healing, as measured by BVF, TMD and ABL, when compared to vehicle + EP. After 6 weeks of treatment, BVF and TMD values in the Scl‐Ab + EP group were similar to those of healthy controls. Serum analysis demonstrated higher levels of bone formation markers osteocalcin and PINP in Scl‐Ab treatment groups. Scl‐Ab restored alveolar bone mass following experimental periodontitis. These findings warrant further exploration of Scl‐Ab therapy in this and other oral bone defect disease scenarios.

LMP1 regulates periodontal ligament progenitor cell proliferation and differentiation

LMP1 is an intracellular scaffold protein that contains a PDZ domain and three LIM domains. LMP1 has multiple functions including regulating mesenchymal stem cell (MSC) osteogenesis. Gene delivery of LMP1 induces bone formation in vivo in heterotopic and orthotopic sites. However, little is known about the physiological function and gene regulatory mechanisms of LMP1 in MSCs at the molecular level. Periodontal ligament (PDL) cells are a unique progenitor cell population that can differentiate into multiple cell types, including osteoblasts, adipocytes, or chondrocytes. This study sought to determine the physiological function and gene regulatory mechanisms of LMP1 in PDL cells at the molecular level. We show that LMP1 is upregulated in early stage of PDL cell osteogenic differentiation. Stable gene knockdown of LMP1 by shRNA inhibits DNA synthesis and corresponding cell proliferation in PDL cells, and further leads to decreased mineralization in vitro. Overexpression of LMP1 increases cell proliferation, and PDZ and ww-interacting domains are not sufficient to mediate this effect. Further, we found that in PDL cells, LMP1 is a downstream target gene of TGF-beta1 that is an early signal critical in preosteoblast proliferation and differentiation. TGF-beta1 stimulates PDL cell proliferation, however, this effect is compromised when LMP1 is knocked down. We further identified that the activation of TAK1-JNK/p38 kinase cascade is involved in the LMP1 gene regulation by TGF-beta1. We conclude that LMP1 is a downstream gene of TGF-beta1, involved in PDL cell proliferation. Our findings advance the understanding of the physiological function of LMP1 and define a regulatory mechanism of LMP1 in PDL progenitor cells and other MSCs.

Surgical periodontal therapy with and without initial scaling and root planing in the management of chronic periodontitis: a randomized clinical trial

AIM To compare the outcomes of surgical periodontal therapy with and without initial scaling and root planing. METHODS Twenty-four patients with severe chronic periodontitis were enrolled in this pilot, randomized controlled clinical trial. Patients were equally allocated into two treatment groups: Control group was treated with scaling and root planing, re-evaluation, followed by Modified Widman Flap surgery and test group received similar surgery without scaling and root planing. Clinical attachment level, probing depth and bleeding on probing were recorded. Standardized radiographs were analysed for linear bone change from baseline to 6 months. Wound fluid inflammatory biomarkers were also assessed. RESULTS Both groups exhibited statistically significant improvement in clinical attachment level and probing depth at 3 and 6 months compared to baseline. A statistically significant difference in probing depth reduction was found between the two groups at 3 and 6 months in favour of the control group. No statistically significant differences in biomarkers were detected between the groups. CONCLUSIONS Combined scaling and root planing and surgery yielded greater probing depth reduction as compared to periodontal surgery without initial scaling and root planing.

LIM DOMAIN PROTEIN-3 (LMP3) COOPERATES WITH BMP7 TO PROMOTE TISSUE REGENERATION BY LIGAMENT PROGENITOR CELLS

Gene transfer of key regulators of osteogenesis for mesenchymal stem cells represents a promising strategy to regenerate bone. It has been reported that LMP3, a transcription variant of LIM domain mineralization protein (LMP) lacking LIM domains, can induce osteogenesis in vitro and in vivo. As little is known about the effects of LMP3 gene therapy on periodontal ligament (PDL) cell osteogenic differentiation, this study sought to explore whether gene delivery of LMP3 can promote PDL cell mineralization and bone formation. Our results showed that adenoviral mediated gene transfer of LMP3 (AdLMP3) significantly upregulated ALP (Alkaline Phosphatase), BSP (Bone Sialoprotein) and BMP2 gene expression and increased in vitro matrix mineralization in human PDL. Although AdLMP3 gene delivery to PDL cells did not induce ectopic bone formation in vivo, we found that AdLMP3 augments new bone formation, which co-delivered with AdBMP7 gene transfer. Our study provides the evidence that there is a synergistic effect between LMP3 and BMP-7 in vivo, suggesting that LMP3 delivery may be used to augment BMP-mediated osteogenesis. LMP3 and BMP-7 combinatory gene therapy may also have specific applications for oral and periodontal regenerative medicine.