Bone is a dynamic tissue that continually undergoes new bone formation (by osteoblasts) and old bone resorption (by osteoclasts); their rates are in balance throughout all life stages, but a gradual loss of bone density occurs with aging. In some people, an abnormal balance of bone loss occurs (osteoporosis), with a lifetime risk of fracture of the hip, spine, or forearm of 40% in white women and 13% in white men age >50 years.[1,2] Osteoporosis is a systemic disease and silent epidemic that is usually diagnosed at a late stage, frequently after a fracture. Bone mineral density (BMD) loss associated with osteoporosis can be measured reliably by dual photon absorptiometry (DPA), quantitative computed tomography (QCT), or dual energy X-ray absorptiometry (DEXA).[1,2,3,4] Although these diagnostic methods measure BMD accurately, they are expensive and time- and energy-intensive compared to point-of-care tests; moreover, the hardware is not amenable to miniaturization. Similarly, biomarkers excreted in serum or urine, usually assessed by enzyme linked immunoassay (ELISA) laboratory testing, are not offered for routine screening and treatment follow-up for time and cost reasons. To address these limitations, and as a simple, noninvasive, easy-to-use, cost- effective, and routine means of diagnosing bone turnover, Intelligent Optical Systems (IOS) is developing a platform based on a simple lateral flow assay (LFTA) technique developed previously by IOS for monitoring salivary markers of bone turnover. This will enable clinicians to perform routine noninvasive screening for osteoporosis in a point-of-care (POC) setting. The simple LFA platform, immobilized with specific reagents sensitive to multiple bone loss salivary biomarkers, is designed to target clinically relevant detection limits n less than 10 min., with the required level of sensitivity and specificity for non-invasive, reliabl screening. The gold standard for validating the study will be absolute and relative BMD as measured by QCT imaging analysis of the lumbar spine (L1-L2) using a phantom with known quantities of hydroxyapatite.[2,3,4] The Phase I research effort established assay platforms for salivary bone loss markers (OC and DPD). The assays exhibited sensitivity that is relevant to clinical requirements, showing a high degree of correlation with patient diagnosis.[5,6] A prospective clinical study confirmed excellent correlation of OC with both bone mineral density (BMD) and the gold standard ELISA biomarker measurement kits for saliva and blood samples. In Phase II we will expand the clinical testing of the established marker detection to include an extensive human prospective study to determine the statistical reliability and the effects of race, age, and diet in a larger population.
A new non-invasive salivary-based bone-loss marker detection platform is proposed for routine screening of bone loss biomarkers via an inexpensive, non-invasive method that can be employed in point-of-care (POC) testing. Routine screening will result in earlier detection of bone loss, which in turn will result in more effective treatmen options, improving the quality of life of osteoporotic patients. The simplicity of the assay technique, and its noninvasiveness, speed, reliability, and low cost, will enable us to position this technology for a number of clinical applications, including prognostic tools for patients unde therapeutic treatment.
