Validity and reliability of the session-RPE method for quantifying training in Australian football: a comparison of the CR10 and CR100 scales.

The purpose of this study was to examine and compare the criterion validity and test-retest reliability of the CR10 and CR100 rating of perceived exertion (RPE) scales for team sport athletes that undertake high-intensity, intermittent exercise. Twenty-one male Australian football (AF) players (age: 19.0 ± 1.8 years, body mass: 83.92 ± 7.88 kg) participated the first part (part A) of this study, which examined the construct validity of the session-RPE (sRPE) method for quantifying training load in AF. Ten male athletes (age: 16.1 ± 0.5 years) participated in the second part of the study (part B), which compared the test-retest reliability of the CR10 and CR100 RPE scales. In part A, the validity of the sRPE method was assessed by examining the relationships between sRPE, and objective measures of internal (i.e., heart rate) and external training load (i.e., distance traveled), collected from AF training sessions. Part B of the study assessed the reliability of sRPE through examining the test-retest reliability of sRPE during 3 different intensities of controlled intermittent running (10, 11.5, and 13 km·h(-1)). Results from part A demonstrated strong correlations for CR10- and CR100-derived sRPE with measures of internal training load (Banisters TRIMP and Edwards TRIMP) (CR10: r = 0.83 and 0.83, and CR100: r = 0.80 and 0.81, p < 0.05). Correlations between sRPE and external training load (distance, higher speed running and player load) for both the CR10 (r = 0.81, 0.71, and 0.83) and CR100 (r = 0.78, 0.69, and 0.80) were significant (p < 0.05). Results from part B demonstrated poor reliability for both the CR10 (31.9% CV) and CR100 (38.6% CV) RPE scales after short bouts of intermittent running. Collectively, these results suggest both CR10- and CR100-derived sRPE methods have good construct validity for assessing training load in AF. The poor levels of reliability revealed under field testing indicate that the sRPE method may not be sensible to detecting small changes in exercise intensity during brief intermittent running bouts. Despite this limitation, the sRPE remains a valid method to quantify training loads in high-intensity, intermittent team sport.

Nanopatterned Titanium Implants Accelerate Bone Formation In Vivo.

Accelerated de novo formation of bone is a highly desirable aim of implants targeting musculoskeletal injuries. To date, this has primarily been addressed by biologic factors. However, there is an unmet need for robust, highly reproducible yet economic alternative strategies that strongly induce an osteogenic cell response. Here, we present a surface engineering method of translating bioactive nanopatterns from polymeric in vitro studies to clinically relevant material for orthopedics: three-dimensional, large area metal. We use a titanium-based sol-gel whereby metal implants can be engineered to induce osteoinduction both in vitro and in vivo. We show that controlled disordered nanotopographies presented as pillars with 15-25 nm height and 100 nm diameter on titanium dioxide effectively induce osteogenesis when seeded with STRO-1-enriched human skeletal stem cells in vivo subcutaneous implantation in mice. After 28 days, samples were retrieved, which showed a 20-fold increase in osteogenic gene induction of nanopatterned substrates, indicating that the sol-gel nanopatterning method offers a promising route for translation to future clinical orthopedic implants.

A review of hydrogel use in fracture healing and bone regeneration.

This review explores the application of hydrogels in orthopaedic clinical situations which may benefit from enhanced growth factor delivery and improved osteogenesis of bone graft material. Hydrogels are defined, and in vivo evidence supporting their application in these clinical areas is explored. Our focus is on clinically pertinent properties, such as the chemistry of formation, biocompatibility, efficacy of cell and growth factor delivery, ability to withstand mechanical loading and potential to be delivered via an injection. Naturally derived hydrogels, such as gelatin, hyaluronic acid and fibroin, together with a number of synthetic polyethylene glycol-based gels combined with protease-sensitive domains, have shown excellent biocompatibility. There is significant literature evidence supporting the ability of hydrogels to facilitate growth factor and cell delivery. Burst release of the selected growth factor remains a consistent challenge, which has been overcome in some studies with chemical modifications of the hydrogel. Interestingly, a number of studies detail percutaneous delivery with hydrogels combined with calcium-based minerals to enhance osteogenicity, with mixed results. Few of the studies explored the biomechanical properties of the materials, and none of the studies reviewed demonstrated the ability of a hydrogel/graft material to withstand mechanical loading in a clinically relevant segmental bone defect model.

Bone Tissue Engineering.

Medical advances have led to a welcome increase in life expectancy. However, accompanying longevity introduces new challenges: increases in age-related diseases and associated reductions in quality of life. The loss of skeletal tissue that can accompany trauma, injury, disease or advancing years can result in significant morbidity and significant socio-economic cost and emphasise the need for new, more reliable skeletal regeneration strategies. To address the unmet need for bone augmentation, tissue engineering and regenerative medicine have come to the fore in recent years with new approaches for de novo skeletal tissue formation. Typically, these approaches seek to harness stem cells, innovative scaffolds and biological factors that promise enhanced and more reliable bone formation strategies to improve the quality of life for many. This review provides an overview of recent developments in bone tissue engineering focusing on skeletal stem cells, vascular development, bone formation and the translation from preclinical in vivo models to clinical delivery.

In Vivo Assessment of Bone Regeneration in Alginate/Bone ECM Hydrogels with Incorporated Skeletal Stem Cells and Single Growth Factors.

The current study has investigated the use of decellularised, demineralised bone extracellular matrix (ECM) hydrogel constructs for in vivo tissue mineralisation and bone formation. Stro-1-enriched human bone marrow stromal cells were incorporated together with select growth factors including VEGF, TGF-ß3, BMP-2, PTHrP and VitD3, to augment bone formation, and mixed with alginate for structural support. Growth factors were delivered through fast (non-osteogenic factors) and slow (osteogenic factors) release PLGA microparticles. Constructs of 5 mm length were implanted in vivo for 28 days within mice. Dense tissue assessed by micro-CT correlated with histologically assessed mineralised bone formation in all constructs. Exogenous growth factor addition did not enhance bone formation further compared to alginate/bone ECM (ALG/ECM) hydrogels alone. UV irradiation reduced bone formation through degradation of intrinsic growth factors within the bone ECM component and possibly also ECM cross-linking. BMP-2 and VitD3 rescued osteogenic induction. ALG/ECM hydrogels appeared highly osteoinductive and delivery of angiogenic or chondrogenic growth factors led to altered bone formation. All constructs demonstrated extensive host tissue invasion and vascularisation aiding integration and implant longevity. The proposed hydrogel system functioned without the need for growth factor incorporation or an exogenous inducible cell source. Optimal growth factor concentrations and spatiotemporal release profiles require further assessment, as the bone ECM component may suffer batch variability between donor materials. In summary, ALG/ECM hydrogels provide a versatile biomaterial scaffold for utilisation within regenerative medicine which may be tailored, ultimately, to form the tissue of choice through incorporation of select growth factors.