Biomedical subjects

Ronald F Zernicke

Publications and source records attributed to Ronald F Zernicke.

18 recordsLinked to original sources

PubMed2005

Imparting mineral affinity to proteins with thiol-labile disulfide linkages.

Chemical conjugation of bisphosphonates (BPs) to proteins is an effective means to enhance binding of proteins to mineral-containing biomaterials. BPs linked to proteins with reversible (i.e., cleavable) linkages were considered desirable over the conjugates linked with stable linkages because cleavable linkages allow protein release in free form from the mineral-containing biomaterials. To explore the feasibility of creating cleavable BP-protein conjugates, an amine- and a thiol-containing BP were conjugated to the model protein Bovine Serum Albumin (BSA) with N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), which resulted in disulfide-linked BP-BSA conjugates. Although disulfide-linked conjugates were stable under aqueous conditions, the conjugates in solution were readily cleaved in the presence of physiological concentrations (approximately 0.3 mM) of the thiol compound, cysteine. The imparted mineral affinity as a result of BP conjugation, as assessed by hydroxyapatite (HA) binding in vitro, was lost upon cleavage of the disulfide-linked BP. The conjugates bound to HA were also cleavable with cysteine, but their cleavage rate was significantly reduced as compared to the conjugates in solution. In conclusion, disulfide-linked BP conjugates were shown to be readily cleavable by the amino acid cysteine and this resulted in the loss of imparted mineral affinity of the proteins. The proposed approach will be useful for modulating in vivo delivery of proteins implanted with mineral-containing biomaterials.

Animals↗

PubMed2005

Comparison of home versus physical therapy-supervised rehabilitation programs after anterior cruciate ligament reconstruction: a randomized clinical trial.

BACKGROUND: Because of health care funding and policy changes, there is a need to examine the effects of an evolution toward patient-directed (ie, home-based) rehabilitation programs on clinical outcomes of patients undergoing anterior cruciate ligament reconstruction. HYPOTHESIS: There will be no difference in the effectiveness of a home-based rehabilitation program and a standard physical therapy-supervised rehabilitation program in patients 3 months after nonacute anterior cruciate ligament reconstruction with bone-patellar tendon-bone grafts. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: There were 145 patients (16-59 years) who attended a presurgery education class. Home-based patients attended 4 physical therapy sessions, and physical therapy-supervised patients attended 17 physical therapy sessions over the first 12 weeks after surgery. All patients followed the same standardized rehabilitation program. Study outcome measures included active-assisted knee flexion and passive knee extension range of motion, knee range of motion during walking, KT computerized arthrometer results, and isokinetic quadriceps and hamstrings strength. Patient outcomes were dichotomized as either clinically acceptable or unacceptable. Rehabilitation programs were compared by the proportion of acceptable patients in each group. RESULTS: The home-based group had a significantly higher percentage of patients with acceptable flexion and extension range of motion compared to the standard physical therapy group (flexion, 67% vs 47%; extension, 97% vs 83%). There were no significant differences between the groups in range of motion during walking, ligament laxity, and strength. CONCLUSION: A structured, minimally supervised rehabilitation program was more effective in achieving acceptable knee range of motion in the first 3 months after anterior cruciate ligament reconstruction than a standard physical therapy-based program. CLINICAL RELEVANCE: Recreational athletes undergoing nonacute anterior cruciate ligament reconstruction can successfully reach acceptable rehabilitation goals in the first 3 months after surgery with a limited number of purposeful physical therapy education sessions, allowing recreational athletes more flexibility when integrating the necessary postoperative rehabilitation into their daily activities.

Adolescent↗

PubMed2005

Designing proteins for bone targeting.

Protein-based therapeutic agents intended for bone diseases should ideally exhibit a high affinity to bone tissue, so that their systemic administration will result in specific delivery to bone with minimal distribution to extra-skeletal sites. This was shown possible in the authors' lab by modifying a desired protein with bisphosphonates (BPs) that exhibit an exceptionally high affinity to the bone-mineral hydroxyapatite. In this review, we explore the potential applications of that concept by summarizing the bone diseases and candidate proteins that will benefit from the proposed bone delivery approach. A selective synopsis of BP synthesis is presented to highlight the synthesis of functional BPs suitable for covalent attachment to proteins. Finally, we present a summary of recent research results from the authors' laboratory emphasizing factors influencing bone affinity of the conjugates. We conclude with future research avenues that are considered critical for clinical entry of the BP-targeted therapeutic agents.

Animals↗

PubMed2005

Strain rate influences periosteal adaptation in mature bone.

Mechanical forces influence bone form and function. Although the adaptive capabilities of bone are well known, the nuances of the mechanical stimuli regulating adaptation remain elusive. Recently, it was suggested that strain rate influences bone adaptation, and impact exercises with high strain rates during growth may be more osteogenic than low impact aerobic exercises. Building on those findings, we hypothesized that higher rates of mechanical loading would evoke greater adaptive responses than lower rates of loading in mature bone. To test that hypothesis, skeletally mature (16 weeks) female C57BL/6 mice underwent non-invasive exogenous cantilever bending of the right tibia with a 1 Hz trapezoidal waveform for 60 s, 5 days per week, for 4 weeks. Loading was calibrated (strain gauge) to induce peak magnitudes of 1000 microepsilon on the lateral tibial middiaphysis. Mice were randomly assigned to three groups based on strain rate of the applied load: low (0.004 s(-1); n = 14), medium (0.020 s(-1); n = 15), and high (0.100 s(-1); n = 14). Calcein injections (i.p., 10 mg kg(-1)) permitted histomorphometric analyses of bone formation. Loading significantly enhanced periosteal mineral apposition rate (MAR), mineralizing surface (MS), and bone formation rate (BFR BS(-1)) in all three strain rate groups, relative to control tibiae. Furthermore, a graded dose-response relation was observed between the applied strain rate and periosteal BFR BS(-1). These increases in MAR, MS, and BFR BS(-1) were not seen on the endosteal surface. Endosteal adaptation was not statistically different between loaded and control tibiae in most endosteal indices of bone adaptation. Moreover, endosteal adaptation did not increase with strain rate. Understanding the nature of the stimuli to which bone cells respond to may underpin the development of non-pharmacological treatments devised to enhance bone mass.

Adaptation, Physiological↗

PubMed2004

Dietary restriction does not adversely affect bone geometry and mechanics in rapidly growing male wistar rats.

The present study assessed the effects of dietary restriction on tibial and vertebral mechanical and geometrical properties in 2-mo-old male Wistar rats. Two-month-old male Wistar rats were randomized to the ad libitum (n=8) or the 35% diet-restricted (DR) feeding group (n=9) for 5 mo. Tibiae and L6 vertebrae were dissected out for microcomputed tomography (microCT) scanning and subsequently fractured in biomechanical testing to determine geometrical and mechanical properties. The DR group had significantly lower mean tibial length, mass, area, and cross-sectional moment of inertia, as well as vertebral energy to maximal load. After adjustment for body mass, however, DR tibial mean maximal load and stiffness, and DR vertebral area, height, volume, and maximal load were significantly greater, relative to ad libitum means. No significant differences were found between the DR and ad libitum mineral ash fractions. Because the material properties of the tibiae between the two groups were not significantly different, presumably the material integrity of the bones was not adversely affected as a consequence of DR. The similar material characteristics were consistent with mineral ash fractions that were not different between the two groups. Vertebral maximal load and stiffness were not significant between the DR and ad libitum animals. Importantly, we show that a level of dietary restriction (35%) that is less severe than many studies (40%), and without micronutrient compensation does not adversely affect tibial and vertebral mechanical properties in young growing male rats when normalized for body mass.

Animal Feed↗

PubMed2004

Systemic bone formation with weekly PTH administration in ovariectomized rats.

PURPOSE: Weekly subcutaneous administration of 0 (vehicle), 10 and 80 microg/kg doses of human parathyroid hormone (1-34) [PTH (1-34)] were compared based on their capacity to induce systemic formation of bone in 9 month-old ovariectomized (OVX) Sprague-Dawley rats. METHODS: Changes elicited at bone tissue after 4 weeks of treatment were assessed using dual x-ray absorptiometry, micro-computed tomography (microCT), and ashing. RESULTS: The 10 microg/kg dose led to a significant increase (p<0.025) in femoral bone mineral density (BMD) over vehicle- and 80 microg/kg-treated groups. Similarly, structural analysis of the femoral neck trabecular bone by microCT revealed increases in bone volume fraction and trabecular thickness over the pre-treatment baseline, and vehicle- and 80 microg/kg-treated groups. CONCLUSIONS: The data suggest that the weekly administration of 10 microg/kg of PTH (1-34) was sufficient to significantly promote the bone mineral density systemically. The weekly administration of 10 microg/kg over a 4-week treatment period is, to our knowledge, one of the lowest reported total dose of PTH (1-34) shown to induce a net anabolic effect on skeletal tissue in OVX rats.

Animals↗

PubMed2004

Rest insertion combined with high-frequency loading enhances osteogenesis.

Mechanical loading can significantly affect skeletal adaptation. High-frequency loading can be a potent osteogenic stimulus. Additionally, insertion of rest periods between consecutive loading bouts can be a potent osteogenic stimulus. Thus we investigated whether the insertion of rest-periods between short-term high-frequency loading bouts would augment adaptation in the mature murine skeleton. Right tibiae of skeletally mature (16 wk) female C57BL/6 mice were loaded in cantilever bending at peak of 800 microepsilon, 30 Hz, 5 days/wk for 3 wk. Left tibiae were the contralateral control condition. Mice were randomly assigned into one of two groups: continuous high-frequency (CT) stimulation for 100 s (n = 9), or 1-s pulses of high-frequency stimuli followed by 10 s of rest (RI) for 100 s (n = 9). Calcein labels were administered on days 1 and 21; label incorporation was used to histomorphometrically assess periosteal and endosteal indexes of adaptation. Periosteal surface referent bone formation rate (pBFR/BS) was significantly enhanced in CT (>88%) and RI (>126%) loaded tibiae, relative to control tibiae. Furthermore, RI tibiae had significantly greater pBFR/BS, relative to CT tibiae (>72%). The endosteal surface was not as sensitive to mechanical loading as the periosteal surface. Thus short-term high-frequency loading significantly elevated pBFR/BS, relative to control tibiae. Furthermore, despite the 10-fold reduction in cycle number, the insertion of rest periods between bouts of high-frequency stimuli significantly augmented pBFR/BS, relative to tibiae loaded continually. Optimization of osteogenesis in response to mechanical loading may underpin the development of nonpharmacological regiments designed to increase bone strength in individuals with compromised bone structures.

Adaptation, Physiological↗

PubMed2004

Cane-assisted gait biomechanics and electromyography after total hip arthroplasty.

OBJECTIVE: To quantify the effects of cane use during walking on hip joint kinematics, kinetics, and muscle activity patterns after unilateral total hip arthroplasty (THA). DESIGN: Nonrandomized experimental design. SETTING: Urban inpatient hospital. PARTICIPANTS: Adults (n=9 men, 2 women) with no history of orthopedic or neuromuscular disease who underwent elective unilateral THA. INTERVENTION: Gait was assessed preoperatively and 4 and 8 months postoperatively. MAIN OUTCOME MEASURES: Three-dimensional hip joint motion and moments and electromyographic patterns of gluteus medius, tensor fascia latae, lateral hamstring, and vastus lateralis were measured during level walking, with and without use of a straight cane. RESULTS: When a cane was held in the contralateral hand, the abduction moment of the affected hip decreased by 26%, whereas that of the contralateral hip increased by 28%. Use of a cane in THA rehabilitation is important because it reduces the load on the operative hip so that bone and soft tissues can heal. Our results suggest that load reduction was successful on the operative side, but the loads on the contralateral side were increased. CONCLUSIONS: After unilateral arthroplasty, subjects using a cane had increased hip abduction moments on the nonoperative hip and decreased hip abduction moments on the operative hip. Clinicians should be mindful of the effects of cane use on the contralateral hip.

Arthroplasty, Replacement, Hip↗

PubMed2004

Doxycycline effects on mechanical and morphometrical properties of early- and late-stage osteoarthritic bone following anterior cruciate ligament injury.

As posttraumatic osteoarthritis (OA) progresses, the mechanical and morphometrical properties of the subchondral bone change and may be linked to damage of the articular cartilage. Potentially to slow that progression, doxycycline was administered orally twice daily (4 mg.kg(-1).day(-1)) in skeletally mature canines after anterior cruciate ligament transection (ACLX). To test if doxycycline significantly altered the structure and function of OA bone, we tested cancellous bone mechanical properties, measured bone mineral content, and analyzed bone structure by microcomputed tomography. Our investigation focused on subchondral trabecular bone changes in the medial femoral condyle at 36 and 72 wk after ACLX. Significant mechanical changes discovered at 36 wk post-ACLX were less obvious at 72 wk in both treated and ACLX groups. Doxycycline treatment conserved bone strain energy density at 72 wk. Doxycycline had little effect on the degradation of superficial osseous tissue at 36 wk post-ACLX; by 72 wk, doxycycline in an ACLX model limited subchondral bone loss within the first 3 mm of periarticular bone with established OA. Significant bone loss occurred in the deeper trabecular bone for all groups. Substantial architectural adaptation within deeper trabecular bone accompanied changes in mechanics in early and established OA.

Animals↗

PubMed2003

Selected contribution: Bone adaptation with aging and long-term caloric restriction in Fischer 344 x Brown-Norway F1-hybrid rats.

Rodents are commonly used as models for human aging because of their relatively short life span, the ease of obtaining age-specific tissue samples, and lower cost. However, age-associated disease may confound inbred animal studies. For example, numerous physiologically significant lesions, such as chronic nephropathy, are more common in aged Fischer 344 (F344) rats than in other strains (Bronson RT, Genetic Effects of Aging, 1990). Conversely, F344 x Brown-Norway F1-hybrid (F344BN) rats, developed by the National Institute on Aging for aging research, live considerably longer and have fewer pathologies at any given age vs. inbred strains (Lipman RD, Chrisp CE, Hazzard DG, and Bronson RT, J Gerontol A Biol Sci Med Sci 51: 54-59, 1996). To our knowledge, there are no data regarding the effect of age on bone geometry and mechanics in this strain of rat. Furthermore, caloric restriction (CR) extends the mean and maximal life span of animals and significantly reduces age-associated disease but may have adverse consequences for bone growth and mechanics. Thus we investigated the effects of age and CR on bone geometry and mechanics in the axial and appendicular skeleton of F344 Brown-Norway rats. Ad libitum fed rats were assessed at 8 mo (young adult; n = 6), 28 mo (late middle age; n = 5), and 36 mo (senescence; n = 6). CR rats were assessed at 28 mo (n = 6). Tibiae and the sixth lumbar vertebrae (L6) were dissected, scanned (micro-computed tomography) to determine geometry, and tested mechanically. From 8 to 36 mo, there were no significant changes in L6 geometry, and only the cross-sectional moment of inertia changed (increased) with the tibia. CR-induced body mass reductions accounted for changes in L6 load at proportional limit, maximal load, and stiffness (structural properties), but altered tibial structural properties were independent of body mass. In tibiae, geometric changes dominated alterations in structural properties. Those data demonstrated that, whereas aging in ad libitum-fed animals induced minor changes in bone mechanics, axial and appendicular bones were adversely influenced by CR in late-middle-aged animals in different manners.

Adaptation, Physiological↗

PubMed2003

Imparting bone affinity to glycoproteins through the conjugation of bisphosphonates.

PURPOSE: To develop a novel means of conjugating bisphosphonates onto the carbohydrate moieties of glycoproteins to enhance protein affinity to bone. METHODS: 1-Amino-1,1-diphosphonate methane (aminoBP) was conjugated onto the carbohydrate moietites of oxidized fetuin by using 4-(maleimidomethyl)cyclohexane-1-carboxyl-hydrazide (MMCCH). Bone affinity of the resulting conjugates was compared to proteins obtained from another means of conjugation, whereby aminoBP was conjugated onto fetuin's lysine moieties by using succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (SMCC). RESULTS: The use of the MMCCH resulted in the conjugation of up to seven aminoBPs per molecule of fetuin. These conjugates gave a 2.6-, 2.0-, 30.5-. and 1.84-fold increased affinity for untreated, ashed, demineralized bone and hydroxyapatite, respectively, as compared to conjugates from the SMCC reaction. Both conjugates exhibited a pH-independent, equally slow degradation in adult bovine serum-containing media. CONCLUSION: The use of the MMCCH chemistry to conjugate aminoBP onto fetuin was feasible. Furthermore, the described processes of conjugation resulted in amino-BP-dependent increase in the glycoprotein's affinity to various bone matrices in a manner that exceeds the affinity produced by the previously established method, which used SMCC.

Animals↗

PubMed2002

Indices of torso asymmetry related to spinal deformity in scoliosis.

OBJECTIVE: To develop indices that quantify 360 degrees torso surface asymmetry sufficiently well to estimate the Cobb angle of scoliotic spinal deformity within the clinically important 5-10 degrees range. DESIGN: Prospective study in 48 consecutive adolescent scoliosis patients (Cobb angles 10-71 degrees ). BACKGROUND: Scoliotic surface asymmetry has been quantified on the back surface by indices such as back surface rotation (BSR) and curvature of the spinous process line and torso centroid line, though with limited success in spinal deformity estimation. Quantification of 360 degrees torso shape may enhance surface-spine correlation and permit reduced use of harmful X-rays in scoliosis. METHODS: For each patient a 3D torso surface model was generated concurrently with postero-anterior X-rays. We computed indices describing principal axis orientation, back surface rotation, and asymmetry of the torso centroid line, left and right half-areas and the spinous process line. We calculated correlations of each index to the Cobb angle and used stepwise regression to estimate the Cobb angle. RESULTS: Several torso asymmetry indices correlated well to the Cobb angle (r up to 0.8). The Cobb angle was best estimated by age, rib hump and left-right variation in torso width in unbraced patients and by centroid lateral deviation in braced patients. A regression model estimated the Cobb angle from torso indices within 5 degrees in 65% of patients and 10 degrees in 88% (r=0.91, standard error=6.1 degrees ). CONCLUSION: Consideration of 360 degrees torso surface data yielded indices that correlated well to the Cobb angle and estimated the Cobb angle within 10 degrees in 88% of cases. RELEVANCE: The torso asymmetry indices developed here show a strong surface-spine relation in scoliosis, encouraging development of a model to detect scoliosis magnitude and progression from the surface shape with minimal X-ray radiation.

Adolescent↗

PubMed2002

Comparison of Cobb angles measured manually, calculated from 3-D spinal reconstruction, and estimated from torso asymmetry.

While scoliotic spinal deformity is traditionally measured by the Cobb angle, we seek to estimate scoliosis severity from the torso surface without X-ray radiation. Here, we measured the Cobb angle in three ways: by protractor from postero-anterior X-ray, by computer from a 3-D digitized model of the vertebral body line, and by neural-network estimation from indices of torso surface asymmetry. The estimates of the Cobb angle by computer and by neural network were equally accurate in 153 records from 52 patients (standard deviation of 6 degrees from the Cobb angle, r=0.93), showing that torso asymmetry reliably predicted spinal deformity. Further improvements in predictive accuracy may require estimation of other 3-D indices of spinal deformity besides the Cobb angle with its wide measurement variability.

Adolescent↗

PubMed2002

Relation between ankle joint dynamics and patellar tendinopathy in elite volleyball players.

OBJECTIVE: Ankle joint complex dynamics developed during volleyball spike jumps take-offs and landings were quantified to assess potential relations between these joint dynamics and patellar tendinopathy. DESIGN: Three-dimensional kinematic data provided information about movements of the lower limbs, while the kinetic data permitted analysis of ground reaction forces as players took-off and landed from full-speed spike jumps. SETTING: Simulated volleyball court with net in a biomechanics research laboratory. PARTICIPANTS: 10 members of the Canadian Men's National Volleyball Team. From history and physical examination, 3 of the 10 players had patellar tendon pain associated with activity and were diagnosed with patellar tendinopathy at the time of the study. Investigators were blinded about the injury status of the players. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Three-dimensional kinematics and joint moments of the ankle, knee, and hip joints. RESULTS: Our analysis revealed that maximal external tibial rotation occurred at or near maximal dorsiflexion while maximal internal tibial rotation coincided with maximal plantarflexion. The plantarflexion moment was 3 to 10 times greater than all the other moments measured, with the maximal plantarflexor moment being calculated at 0.4 BWm (360 Nm). In blinded logistic regression analyses, we found one of the dynamics variables (inversion moment during the landing of the spike jump) was a significant predictor of patellar tendinopathy. CONCLUSIONS: Coupling the results of the current analysis of ankle joint complex dynamics with previously reported results of knee joint dynamics related to patellar tendinopathy suggests that a cluster of variables linked to patellar tendinopathy includes: high ankle inversion-eversion moments, high external tibial rotation and plantarflexion moments, large vertical ground reaction forces, and high rate of knee extensor moment development.

Adult↗

PubMed2002

Genetic algorithm-neural network estimation of cobb angle from torso asymmetry in scoliosis.

Scoliosis severity, measured by the Cobb angle, was estimated by artificial neural network from indices of torso surface asymmetry using a genetic algorithm to select the optimal set of input torso indices. Estimates of the Cobb angle were accurate within 5 degrees in two-thirds, and within 10 degrees in six-sevenths, of a test set of 115 scans of 48 scoliosis patients, showing promise for future longitudinal studies to detect scoliosis progression without use of X-rays.

Abdomen↗

PubMed2002

Mechanical and architectural bone adaptation in early stage experimental osteoarthritis.

The purpose of this study was to quantify mechanical and architectural changes to knee joint periarticular subchondral cancellous bone in early stage experimental osteoarthritis (OA). Unilateral anterior cruciate ligament transection (ACLX) was performed on 10 dogs that were assigned randomly to two groups: 3 weeks or 12 weeks post-ACLX. Cylindrical bone cores excised from the medial condyle of the distal femur after death were scanned using high-resolution microcomputed tomography (muCT) and subsequently failed under unconstrained uniaxial compression. The apparent-level elastic modulus was less in the ACLX femur compared with the contralateral control, and the decrease was significant (-45%; p < 0.05) by 12-weeks post-ACLX. A finite element (FE) analysis based on muCT data simulated the uniaxial compression tests on a specimen-by-specimen basis to determine tissue modulus. No change in tissue modulus was detected, and a single tissue modulus of 5100 MPa (95% CI, +/- 600 MPa) explained the apparent-level modulus changes observed in the disease-related bone adaptation. The three-dimensional (3D) connectivity was evaluated from the original muCT data to quantify architectural alterations in contrast to tissue alterations. Significantly increased connectivity (through plate perforations) occurred as early as 3 weeks post-ACLX and was as high as 127% by 12 weeks post-ACLX in the distal femur. These measured changes indicated that architectural adaptation predominated over tissue modulus changes affecting apparent-level elastic modulus in the early stage of experimental OA and suggests that to maintain normal cancellous bone after a traumatic injury, early intervention should focus on preventing the substantial architectural alterations.

Adaptation, Physiological↗

PubMed2002

Prediction of spinal deformity in scoliosis from geometric torsion.

The shape of a curved line that passes through thoracic and lumbar vertebrae is often used to study spinal deformity with measurements in "auxiliary" planes that are not truly three-dimensional (3D). Here we propose a new index, the geometric torsion, which could uniquely describe the spinal deformity. In this study we assessed whether geometric torsion could be effectively used. to predict spinal deformity with the aid of multiple linear regression. Anatomical landmarks were obtained from multi-view radiographic reconstruction and used to generate 3D model of the spine and rib cage of 28 patients. Fourier series best fitted to the vertebral centroids approximated the spinal shape. For each patient, spinal deformity indices were computed. Torsion was calculated and 20 derived parameters were recorded. Torsion inputs were used in a multiple linear regression model for prediction of key spinal indices. The primary clinical Cobb angle (mainly thoracic) was predicted well, with r=0.89 using all 20 inputs of torsion or r=0.83 using just two. Torsion was also well related to the orientation of plane of maximal deformity (r=0.87). Torsion was less accurate but still significant in predicting maximal vertebral axial rotation (r=0.77). This preliminary study showed promising results for the use of geometric torsion as an alternative 3D index of spinal deformity.

Adolescent↗

PubMedDate not supplied

Bone marrow cells from normal and ovariectomized rats respond differently to basic fibroblast growth factor and bone morphogenetic protein 2 treatment in vitro.

The protein growth factors basic fibroblast growth factor (bFGF) and bone morphogenetic protein 2 (BMP-2) are being actively pursued for bone tissue engineering. Although both proteins are capable of stimulating osteogenic activity of bone marrow cells (BMCs), no studies have addressed the effect of estrogen deficiency on the growth factor responsiveness of BMCs. This study investigated the osteogenic response of BMCs from normal and ovariectomized (OVX) rats to bFGF and BMP- 2. In the absence of growth factors, a higher number of total colony-forming units (t-CFU) and alkaline phosphatase-expressing CFU (ALP-CFU) were obtained with BMCs derived from OVX rats. The percentage of ALP-CFU, however, was not significantly different between BMCs from the two groups of rats. Whereas BMP-2 did not influence the t-CFU and percentage of ALP-CFU, bFGF decreased t-CFU in BMCs derived from OVX rats and reduced the percentage of ALP-CFU in BMCs from both types of rats. Consistent with the higher t-CFU, the number of mineralized colonies (min-CFU) was also higher for BMCs derived from OVX rats. The number of min-CFU was not influenced by BMP-2 treatment, but was reduced with bFGF treatment. Comparison of the growth factor effects on a per-cell (DNA) basis confirmed the expected stimulatory effect of BMP-2 on ALP activity and mineralization in BMCs from normal rats, but these two parameters were not unequivocally stimulated in BMCs from OVX rats. We conclude that BMCs derived from normal and OVX rats exhibited significant differences in their osteogenic response to bFGF and BMP-2 treatment.

Animals↗