Multiple ParA/MinD ATPases coordinate the positioning of disparate cargos in a bacterial cell.

In eukaryotes, linear motor proteins govern intracellular transport and organization. In bacteria, where linear motors involved in spatial regulation are absent, the ParA/MinD family of ATPases organize an array of genetic- and protein-based cellular cargos. The positioning of these cargos has been independently investigated to varying degrees in several bacterial species. However, it remains unclear how multiple ParA/MinD ATPases can coordinate the positioning of diverse cargos in the same cell. Here, we find that over a third of sequenced bacterial genomes encode multiple ParA/MinD ATPases. We identify an organism (Halothiobacillus neapolitanus) with seven ParA/MinD ATPases, demonstrate that five of these are each dedicated to the spatial regulation of a single cellular cargo, and define potential specificity determinants for each system. Furthermore, we show how these positioning reactions can influence each other, stressing the importance of understanding how organelle trafficking, chromosome segregation, and cell division are coordinated in bacterial cells. Together, our data show how multiple ParA/MinD ATPases coexist and function to position a diverse set of fundamental cargos in the same bacterial cell.

Simple and Low-Cost Electroactive Membranes for Ammonia Recovery.

Ammonia is considered a contaminant to be removed from wastewater. However, ammonia is a valuable commodity chemical used as the primary feedstock for fertilizer manufacturing. Here we describe a simple and low-cost ammonia gas stripping membrane capable of recovering ammonia from wastewater. The material is composed of an electrically conducting porous carbon cloth coupled to a porous hydrophobic polypropylene support, that together form an electrically conductive membrane (ECM). When a cathodic potential is applied to the ECM surface, hydroxide ions are produced at the water-ECM interface, which transforms ammonium ions into higher-volatility ammonia that is stripped across the hydrophobic membrane material using an acid-stripping solution. The simple structure, low cost, and easy fabrication process make the ECM an attractive material for ammonia recovery from dilute aqueous streams, such as wastewater. When paired with an anode and immersed into a reactor containing synthetic wastewater (with an acid-stripping solution providing the driving force for ammonia transport), the ECM achieved an ammonia flux of 141.3 ± 14.0 g.cm-2.day-1 at a current density of 6.25 mA.cm-2 (69.2 ± 5.3 kg(NH3-N)/kWh). It was found that the ammonia flux was sensitive to the current density and acid circulation rate.

The Novel Oxazolidinone TBI-223 Is Effective in Three Preclinical Mouse Models of Methicillin-Resistant Staphylococcus aureus Infection.

Staphylococcus aureus is an important cause of various infections in humans, including bacteremia, skin and soft tissue infections, and infections associated with implanted medical devices. The emergence of hospital- and community-acquired methicillin-resistant Staphylococcus aureus (MRSA) underscores the urgent and unmet need to develop novel, safe, and effective antibiotics against these multidrug-resistant clinical isolates. Oxazolidinone antibiotics such as linezolid have excellent oral bioavailability and provide coverage against MRSA infections. However, their widespread and long-term use is often limited by adverse effects, especially myelosuppression. TBI-223 is a novel oxazolidinone with potentially reduced myelosuppression, compared to linezolid, but its efficacy against MRSA infections is unknown. Therefore, the preclinical efficacy of TBI-223 (80 and 160 mg/kg twice daily) was compared with that of linezolid (40 and 80 mg/kg twice daily) and sham treatment in mouse models of MRSA bacteremia, skin wound infection, and orthopedic-implant-associated infection. The dosage was selected based on mouse pharmacokinetic analysis of both linezolid and TBI-223, as well as measurement of the MICs. In all three models, TBI-223 and linezolid had comparable dose-dependent efficacies in reducing bacterial burden and disease severity, compared with sham-treated control mice. Taken together, these findings indicate that TBI-223 represents a novel oxazolidinone antibiotic that may provide an additional option against MRSA infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans. IMPORTANCE Staphylococcus aureus is the predominant cause of bloodstream, skin, and bone infections in humans. Resistance to commonly used antibiotics is a growing concern, making it more difficult to treat staphylococcal infections. Use of the oxazolidinone antibiotic linezolid against resistant strains is hindered by high rates of adverse reactions during prolonged therapy. Here, a new oxazolidinone named TBI-223 was tested against S. aureus in three mouse models of infection, i.e., bloodstream infection, skin infection, and bone infection. We found that TBI-223 was as effective as linezolid in these three models. Previous data suggest that TBI-223 has a better safety profile than linezolid. Taken together, these findings indicate that this new agent may provide an additional option against MRSA infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans.

Phase I/II study to assess the clinical pharmacology and safety of single ascending and multiple subcutaneous doses of PF-06881894 in women with non-distantly metastatic breast cancer.

PURPOSE: To evaluate the pharmacodynamics (PD), pharmacokinetics (PK), and safety of single and multiple doses of PF-06881894 (pegfilgrastim-apgf; Nyvepria™), a biosimilar to reference pegfilgrastim (Neulasta®), in women with non-distantly metastatic breast cancer. METHODS: In Phase I (Cycle 0) of this Phase I/II study, the PD response (absolute neutrophil count [ANC]; CD34 + count), PK profile, and safety of a single 3- or 6-mg subcutaneous dose of PF-06881894 were assessed in chemotherapy-naïve patients before definitive breast surgery. In Phase II (Cycles 1-4), the PD response (duration of severe neutropenia [DSN, Cycle 1], ANC [Cycles 1 and 4]) and PK profile (Cycles 1 and 4) of single and multiple 6-mg doses of PF-06881894 concomitant with chemotherapy and after definitive breast surgery were assessed. RESULTS: Twenty-five patients (mean age 59 years) were enrolled (Cycle 0, n = 12; Cycles 1-4, n = 13). In Cycle 0, PD responses and PK values were lower with 3-mg versus 6-mg PF-06881894. In Cycles 1 and 4, mean DSN was 0.667 days after single or multiple 6-mg doses of PF-06881894, respectively. In Cycle 4 versus Cycle 1, PD responses were more robust; PK values (mean area under the curve, maximum concentration) were lower; and clearance values were higher. The safety profile of PF-06881894 was similar to that for reference pegfilgrastim. CONCLUSION: PF-06881894 as a single 3- or 6-mg dose prior to definitive surgery, or multiple 6-mg/cycle doses postoperatively, with/without myelosuppressive chemotherapy, was consistent with the clinical pharmacology and safety profile of reference pegfilgrastim. TRIAL REGISTRATION: October 2017. ClinicalTrials.gov Identifier: NCT02650193. EudraCT Number: 2015-002057-35.

Pan-caspase inhibition as a potential host-directed immunotherapy against MRSA and other bacterial skin infections.

Staphylococcus aureus causes most skin infections in humans, and the emergence of methicillin-resistant S. aureus (MRSA) strains is a serious public health threat. There is an urgent clinical need for nonantibiotic immunotherapies to treat MRSA infections and prevent the spread of antibiotic resistance. Here, we investigated the pan-caspase inhibitor quinoline-valine-aspartic acid-difluorophenoxymethyl ketone (Q-VD-OPH) for efficacy against MRSA skin infection in mice. A single systemic dose of Q-VD-OPH decreased skin lesion sizes and reduced bacterial burden compared with vehicle-treated or untreated mice. Although Q-VD-OPH inhibited inflammasome-dependent apoptosis-associated speck-like protein containing caspase activation and recruitment domain (ASC) speck formation and caspase-1-mediated interleukin-1ß (IL-1ß) production, Q-VD-OPH maintained efficacy in mice deficient in IL-1ß, ASC, caspase-1, caspase-11, or gasdermin D. Thus, Q-VD-OPH efficacy was independent of inflammasome-mediated pyroptosis. Rather, Q-VD-OPH reduced apoptosis of monocytes and neutrophils. Moreover, Q-VD-OPH enhanced necroptosis of macrophages with concomitant increases in serum TNF and TNF-producing neutrophils, monocytes/macrophages, and neutrophils in the infected skin. Consistent with this, Q-VD-OPH lacked efficacy in mice deficient in TNF (with associated reduced neutrophil influx and necroptosis), in mice deficient in TNF/IL-1R and anti-TNF antibody-treated WT mice. In vitro studies revealed that combined caspase-3, caspase-8, and caspase-9 inhibition reduced apoptosis, and combined caspase-1, caspase-8, and caspase-11 inhibition increased TNF, suggesting a mechanism for Q-VD-OPH efficacy in vivo. Last, Q-VD-OPH also had a therapeutic effect against Streptococcus pyogenes and Pseudomonas aeruginosa skin infections in mice. Collectively, pan-caspase inhibition represents a potential host-directed immunotherapy against MRSA and other bacterial skin infections.

Factors Influencing Infusion-Related Reactions Following Dosing of Reference Rituximab and PF-05280586, a Rituximab Biosimilar.

BACKGROUND: Infusion-related reactions (IRRs) are the most common adverse event (AE) associated with infusion of rituximab, an anti-CD20 monoclonal antibody. OBJECTIVE: Our objective was to evaluate the impact of dosing/infusion patterns and certain baseline characteristics on IRR occurrence during the first rituximab infusion administered as the biosimilar PF-05280586 (RTX-PF) or reference rituximab sourced from the EU (RTX-EU, MabThera®) in patients with CD20+ low-tumor-burden follicular lymphoma. PATIENTS AND METHODS: Rituximab (RTX-PF, n=196; RTX-EU, n=198) was administered (375 mg/m2) on days 1, 8, 15, and 22 (one cycle), with a follow-up period through 52 weeks. The relationships between infusion rate, drug exposure, and IRR incidence were assessed by logistic regression analysis and pharmacokinetic modeling and simulation. Baseline CD20 level, antidrug antibody (ADA) status, and tumor burden according to IRR occurrence (yes/no) were compared descriptively. RESULTS: Median rituximab infusion duration on day 1 was 3.50 h for each of the two groups. There was a positive correlation between infusion rate and all-grade IRRs occurring within 24 h after infusion (p < 0.0001). Patients who developed IRRs had a higher median baseline CD20+ level. IRR incidence was unaffected by baseline ADA status. Drug exposure did not predict IRR incidence. Baseline tumor burden was similar between patients with and without IRRs. CONCLUSIONS: Results of this analysis provide a better understanding of IRRs after the first rituximab (RTX-PF or RTX-EU) infusion and demonstrate a potential correlation of infusion rate and other factors with IRR at the individual and population levels. Infusion-rate escalation steps continue to be needed to manage IRRs. TRIAL REGISTRATION (DATE OF REGISTRATION): ClinicalTrials.gov Identifier: NCT02213263 (11 August 2014); and EudraCT: 2014-000132-41 (10 October 2014).

Interleukin-1ß and tumor necrosis factor are essential in controlling an experimental orthopedic implant-associated infection.

Orthopedic implant-associated infection (OIAI) is a major complication that leads to implant failure. In preclinical models of Staphylococcus aureus OIAI, osteomyelitis and septic arthritis, interleukin-1α (IL-1α), IL-1ß, and tumor necrosis factor (TNF) are induced, but whether they have interactive or distinctive roles in host defense are unclear. Herein, a S. aureus OIAI model was performed in mice deficient in IL-1α, IL-1ß, or TNF. Mice deficient in IL-1ß or TNF (to a lesser extent) but not IL-1α had increased bacterial burden at the site of the OIAI throughout the 28-day experiment. IL-1ß and TNF had a combined and critical role in host defense as mice deficient in both IL-1R and TNF (IL-1R/TNF-deficient mice) had a 40% mortality rate, which was associated with markedly increased bacterial burden at the site of the OIAI infection. Finally, IL-1α- and IL-1ß-deficient mice had impaired neutrophil recruitment whereas IL-1ß-, TNF-, and IL-1R/TNF-deficient mice all had impaired recruitment of both neutrophils and monocytes. Therefore, IL-1ß and TNF contributed to host defense against S. aureus OIAI and neutrophil recruitment was primarily mediated by IL-1ß and monocyte recruitment was mediated by both IL-1ß and TNF.

Fully Automated Echocardiogram Interpretation in Clinical Practice.

BACKGROUND: Automated cardiac image interpretation has the potential to transform clinical practice in multiple ways, including enabling serial assessment of cardiac function by nonexperts in primary care and rural settings. We hypothesized that advances in computer vision could enable building a fully automated, scalable analysis pipeline for echocardiogram interpretation, including (1) view identification, (2) image segmentation, (3) quantification of structure and function, and (4) disease detection. METHODS: Using 14 035 echocardiograms spanning a 10-year period, we trained and evaluated convolutional neural network models for multiple tasks, including automated identification of 23 viewpoints and segmentation of cardiac chambers across 5 common views. The segmentation output was used to quantify chamber volumes and left ventricular mass, determine ejection fraction, and facilitate automated determination of longitudinal strain through speckle tracking. Results were evaluated through comparison to manual segmentation and measurements from 8666 echocardiograms obtained during the routine clinical workflow. Finally, we developed models to detect 3 diseases: hypertrophic cardiomyopathy, cardiac amyloid, and pulmonary arterial hypertension. RESULTS: Convolutional neural networks accurately identified views (eg, 96% for parasternal long axis), including flagging partially obscured cardiac chambers, and enabled the segmentation of individual cardiac chambers. The resulting cardiac structure measurements agreed with study report values (eg, median absolute deviations of 15% to 17% of observed values for left ventricular mass, left ventricular diastolic volume, and left atrial volume). In terms of function, we computed automated ejection fraction and longitudinal strain measurements (within 2 cohorts), which agreed with commercial software-derived values (for ejection fraction, median absolute deviation=9.7% of observed, N=6407 studies; for strain, median absolute deviation=7.5%, n=419, and 9.0%, n=110) and demonstrated applicability to serial monitoring of patients with breast cancer for trastuzumab cardiotoxicity. Overall, we found automated measurements to be comparable or superior to manual measurements across 11 internal consistency metrics (eg, the correlation of left atrial and ventricular volumes). Finally, we trained convolutional neural networks to detect hypertrophic cardiomyopathy, cardiac amyloidosis, and pulmonary arterial hypertension with C statistics of 0.93, 0.87, and 0.85, respectively. CONCLUSIONS: Our pipeline lays the groundwork for using automated interpretation to support serial patient tracking and scalable analysis of millions of echocardiograms archived within healthcare systems.

A multicenter case registry study on medication-related osteonecrosis of the jaw in patients with advanced cancer.

PURPOSE: This observational case registry study was designed to describe the natural history of cancer patients with medication-related osteonecrosis of the jaw (ONJ) and evaluate the ONJ resolution rate. METHODS: Adults with a diagnosis of cancer and with a new diagnosis of ONJ were enrolled and evaluated by a dental specialist at baseline and every 3 months for 2 years and then every 6 months for 3 years until death, consent withdrawal, or loss to follow-up. The primary endpoint was the rate and time course of ONJ resolution. Secondary endpoints included frequency of incident ONJ risk factors, ONJ treatment patterns, and treatment patterns of antiresorptive agents for subsequent ONJ. RESULTS: Overall, 327 patients were enrolled; 207 (63%) were continuing on study at data cutoff. Up to 69% of evaluable patients with ONJ had resolution or improvement during the study. ONJ resolution (AAOMS ONJ staging criteria) was observed in 114 patients (35%); median (interquartile range) time from ONJ onset to resolution was 7.3 (4.5-11.4) months. Most patients (97%) had received antiresorptive medication before ONJ development, 9 patients (3%) had not; 68% had received zoledronic acid, 38% had received denosumab, and 10% had received pamidronate (56% had received bisphosphonates only, 18% had received denosumab only, and 21% had exposure to both). CONCLUSIONS: These results are consistent with those observed in clinical trials evaluating skeletal-related events in patients with advanced malignancy involving bone. Longer follow-up will provide further information on ONJ recurrence and resolution rates between medically and surgically managed patients.

Determination of mild, moderate, and severe pain interference in patients with cancer.

Effective assessment and management of pain in patients with cancer is strengthened by the patient's report of how much pain interferes with daily functioning. This requires a clear delineation of different levels of pain interference. We derived optimal cutpoints for differentiating between mild, moderate, and severe pain interference assessed by the Brief Pain Inventory (BPI) and describe the prevalence and characteristics of pain-induced functional impairment in patients with cancer. Data were pooled across 3 Phase III pivotal trials. Patient-completed questionnaires included the EuroQol 5 dimensions questionnaire (EQ5D), Functional Assessment of Cancer Therapy-General Measure (FACT-G), and BPI. Optimal cutpoints for categorizing pain interference into 3 levels were derived using analysis of variance, with different cutpoint sets for BPI total interference (BPI-PITS, the average score of all 7 items), activity-related interference (BPI-WAW, the average score of work, general activity, and walking), and mood-related interference (BPI-REM, the average score of relations with others, enjoyment of life, and mood) as independent variables and EQ5D-visual analog scale and total FACT-G score as dependent variables. To validate the cutpoints, we assessed whether interference categories were in concordance with Eastern Cooperative Oncology Group performance status (ECOG-PS) levels. The optimal cutpoints were (2,5) for BPI-PITS, (2,6) for BPI-WAW, and (2,5) for BPI-REM. The mild (<2), moderate (2-5 or 2-6), and severe (>5 or >6) pain interference groups were significantly concordant with ECOG-PS levels (P < 0.0001). We empirically derived patient-reported pain interference categories in relation to clinician-rated performance status. These cutpoints may facilitate the conduct and interpretation of clinical evaluation, symptom epidemiology, and clinical trials.

Discovery of Pyrophosphate Diesters as Tunable, Soluble, and Bioorthogonal Linkers for Site-Specific Antibody-Drug Conjugates.

As part of an effort to examine the utility of antibody-drug conjugates (ADCs) beyond oncology indications, a novel pyrophosphate ester linker was discovered to enable the targeted delivery of glucocorticoids. As small molecules, these highly soluble phosphate ester drug linkers were found to have ideal orthogonal properties: robust plasma stability coupled with rapid release of payload in a lysosomal environment. Building upon these findings, site-specific ADCs were made between this drug linker combination and an antibody against human CD70, a receptor specifically expressed in immune cells but also found aberrantly expressed in multiple human carcinomas. Full characterization of these ADCs enabled procession to in vitro proof of concept, wherein ADCs 1-22 and 1-37 were demonstrated to afford potent, targeted delivery of glucocorticoids to a representative cell line, as measured by changes in glucocorticoid receptor-mediated gene mRNA levels. These activities were found to be antibody-, linker-, and payload-dependent. Preliminary mechanistic studies support the notion that lysosomal trafficking and enzymatic linker cleavage are required for activity and that the utility for the pyrophosphate linker may be general for internalizing ADCs as well as other targeted delivery platforms.

Identification and Characterization of Small-Molecule Inhibitors of the R132H/R132H Mutant Isocitrate Dehydrogenase 1 Homodimer and R132H/Wild-Type Heterodimer.

Recurrent genetic mutations in isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) have been identified in multiple tumor types. The most frequent mutation, IDH1 R132H, is a gain-of-function mutation resulting in an enzyme-catalyzing conversion of α-ketoglutarate (α-KG) to 2-hydroxyglutarate (2-HG). A high-throughput assay quantifying consumption of NADPH by IDH1 R132H has been optimized and implemented to screen 3 million compounds in 1536-well formats. The primary high-throughput screening hits were further characterized by RapidFire-mass spectrometry measuring 2-HG directly. Multiple distinct chemotypes were identified with nanomolar potencies (6-300 nM). All inhibitors were found to be inactive against the wild-type IDH1 homodimers. An IDH1 heterodimer between wild-type and R132H mutant is capable of catalyzing conversion of α-KG to 2-HG and isocitrate to α-KG. Interestingly, one of the inhibitors, EXEL-9324, was found to inhibit both conversions by the IDH1 heterodimer. This indicates the R132H/WT heterodimer may adopt conformations distinct from that of the R132H/R132H homodimer. Further enzymatic studies support this conclusion as the heterodimer exhibited a significantly lower apparent Michaelis-Menten constant for α-KG (K(m)=110 µM) compared with the R132H homodimer (K(m)= 1200 µM). The enhanced apparent affinity for α-KG suggests R132H/WT heterodimeric IDH1 can produce 2-HG more efficiently at normal intracellular levels of α-KG (approximately 100 µM).

Decision trees for identifying predictors of treatment effectiveness in clinical trials and its application to ovulation in a study of women with polycystic ovary syndrome.

BACKGROUND: Double-blind, randomized clinical trials are the preferred approach to demonstrating the effectiveness of one treatment against another. The comparison is, however, made on the average group effects. While patients and clinicians have always struggled to understand why patients respond differently to the same treatment, and while much hope has been held for the nascent field of predictive biomarkers (e.g. genetic markers), there is still much utility in exploring whether it is possible to estimate treatment efficacy based on demographic and baseline variables. METHODS: The pregnancy in polycystic ovary syndrome (PPCOS) study was a prospective, multi-center, randomized clinical trial comparing three ovulation induction regimens: clomiphene citrate (CC), metformin and the combination of the two. There were 446 women who ovulated in response to the treatments among the entire 626 participants. In this report, we focus on the 418 women who received CC (alone or combined with metformin) to determine if readily available baseline physical characteristics and/or easily obtainable baseline measures could be used to distinguish treatment effectiveness in stimulating ovulation. We used a recursive partitioning technique and developed a node-splitting rule to build decision tree models that reflected within-node and within-treatment responses. RESULTS: Overall, the combination of CC plus metformin resulted in an increased incidence of ovulation compared with CC alone. This is particularly so in women with relatively larger left ovarian volumes (≥ 19.5 cubic cm), and a left ovarian volume <19.5 cubic cm was related to treatment outcomes for all subsequent nodes. Women who were older, who had higher baseline insulin, higher waist-to-hip circumference ratio or higher sex hormone-binding globulin levels had better ovulatory rates with CC alone than with the combination of CC plus metformin. CONCLUSIONS: Polycystic ovary syndrome (PCOS) is a phenotypically diverse condition. Both baseline laboratory and clinical parameters can predict the ovulatory response in women with PCOS undergoing ovulation induction. Without a priori hypotheses with regard to any predictors, the observation regarding left ovary volume is novel and worthy of further investigation and validation.

Healing of critically sized femoral defects, using genetically modified mesenchymal stem cells from human adipose tissue.

The FDA has approved the clinical use of recombinant bone morphogenetic proteins (BMPs). However, the use of recombinant BMPs in humans has required large doses of the proteins to be effective, which suggests that the delivery method of bone morphogenetic proteins needs to be optimized. Gene therapy is an alternative method to deliver such recombinant proteins, and gene transfer techniques have been tested on a variety of cell types including bone marrow cells, skin fibroblasts, peripheral blood monocytes, and muscle-derived cells. In this study, we sought to determine the ability of BMP-2-producing human adipose-derived mesenchymal stem cells to heal a critically sized femoral defect in a nude rat model. After approval by the human subjects protection committee, human adipose tissue was obtained from healthy donors. The lipoaspirate was processed as previously described (De Ugarte, D.A., et al. Cells Tissues Organs 174, 101, 2003). Cells were grown in culture and infected with a BMP-2-carrying adenovirus. Five million cells were applied to a collagen- ceramic carrier and implanted into femoral defects as previously described (Zuk, P.A., et al. Mol. Biol. 13, 4279, 2002). All animals were killed at 8 weeks. Femora were dissected out and underwent radiographic, histologic, and biomechanical analysis. Eleven of the 12 femora in the group treated with human processed lipoaspirate (HPLA) cells genetically modified to overexpress BMP-2 had healed at 8 weeks. This was assessed by radiographs, by mechanical testing, and by histology. The one femur that did not heal had a subacute infection. All eight of the femora treated with the rhBMP-2-impregnated collagen-ceramic carrier healed. No statistically significant difference was detected between these two groups. Evaluation of the control groups: group II (collagen- ceramic carrier with HPLA cells) and group III (collagen-ceramic carrier alone) showed that none of the femora had healed by 8 weeks. Our results indicate that HPLA cells genetically modified by adenoviral gene transfer to overexpress BMP-2 can induce bone formation in vivo and heal a critically sized femoral defect in an athymic rat. The HPLA cells alone did not induce significant bone formation. However, when combined with an osteoinductive factor these cells may be an effective method for enhancing bone healing and the tissue engineering of bone.

Genetically modified human derived bone marrow cells for posterolateral lumbar spine fusion in athymic rats: beyond conventional autologous bone grafting.

STUDY DESIGN: This experimental study consisted of four groups. In Group I, 8 animals were implanted with a collagen sponge containing 5 million human-derived bone marrow cells (HBMCs) infected with the BMP-2-containing adenovirus. In Group II, 5 animals were implanted with a collagen sponge containing 5 million HBMCs, which had been infected with an adenovirus containing the cDNA for the lacZ gene. In Group III, 5 animals were implanted with a collagen sponge containing 5 million uninfected HBMCs. In Group IV, 5 animals were implanted with a collagen sponge alone. All animals were killed at 12 weeks. OBJECTIVES: The purpose of this study was to assess the ability of HBMCs infected with a BMP-2 adenovirus to induce a posterolateral spine in an athymic rat model. SUMMARY OF BACKGROUND DATA: High pseudarthrosis rates after attempted spinal arthrodesis as well as the morbidity associated with iliac crest bone graft harvest make alternative bone graft materials desirable. Alternatives include allograft bone, demineralized bone matrices, and more recently, recombinant bone morphogenetic proteins. However, high doses of the recombinant protein are required, and a single dose of recombinant protein may not induce a sufficient osteoinductive response in all patients. An alternative strategy is to genetically manipulate cells to overexpress a bone morphogenetic protein. METHODS: HBMCs grown in culture were infected with an adenovirus containing the cDNA for BMP-2 (AdBMP-2) or the gene for beta-galactosidase (AdlacZ). Cells were implanted on the decorticated transverse processes of L4-L5 as previously described. Rats were assessed by radiographs at 4-week intervals and were killed at 12 weeks. After death, spines were explanted and assessed by manual palpation and histologic analysis. RESULTS: Eight of eight rats implanted with AdBMP-2-infected HBMCs (Group I) were fused by radiographic evaluation and manual palpation at 12 weeks. Control groups consisted of: 5 rats implanted with the collagen sponge alone (Group II), 5 rats implanted with a collagen sponge and 5 million uninfected HBMCs (Group III), and 5 rats implanted with HBMCs infected with AdlacZ (Group IV). None of the rats in the control groups (0 of 15) developed a fusion at L4-L5. CONCLUSION: This study demonstrates that human-derived bone marrow cells can be infected with a BMP-2-containing adenovirus and produce sufficient bone in vivo to fuse the lumbar spine.