Effect of molecular weight and concentration of hyaluronan on cell proliferation and osteogenic differentiation in vitro

Alginate Microcapsules Incorporating Hyaluronic Acid Recreate Closer in Vivo Environment for Mesenchymal Stem Cells

The potential clinical application of alginate cell microencapsulation has advanced enormously during the past decade. However, the 3D environment created by alginate beads does not mimic the natural extracellular matrix surrounding cells in vivo, responsible of cell survival and functionality. As one of the most frequent macromolecules present in the extracellular matrix is hyaluronic acid, we have formed hybrid beads with alginate and hyaluronic acid recreating a closer in vivo cell environment. Our results show that 1% alginate-0.25% hyaluronic acid microcapsules retain 1.5% alginate physicochemical properties. Moreover, mesenchymal stem cells encapsulated in these hybrid beads show enhanced viability therapeutic protein release and mesenchymal stem cells' potential to differentiate into chondrogenic lineage. Although future studies with additional proteins need to be done in order to approach even more the extracellular matrix features, we have shown that hyaluronic acid protects alginate encapsulated mesenchymal stem cells by providing a niche-like environment and remaining them competent as a sustainable drug delivery system.

Efficacy and safety study on a new compound associating low and high molecular weight hyaluronic acid in the treatment of hip osteoarthritis

The combined use of low and high molecular weight hyaluronic acid (HA) has never been reported in the treatment of osteoarthritis (OA). The aim of this paper was to evaluate the efficacy of a new hybrid association of both preparations in patients suffering from hip OA and to compare the results with those obtained retrospectively from a cohort of patients treated with high molecular weight HA.

Twenty patients with moderate-severe hip OA (grade II–IV according to Kellgren-Lawrence score) were enrolled in the study group. After clinical and functional evaluation (Visual Analogue Scale [VAS] for pain, Lequesne Index, Harris Hip Score), each participant received an intra-articular ultrasound-guided injection of the new HA compound at baseline and after 40 days. The measures were repeated at three and six months. The data collected were retrospectively compared with those obtained in a cohort of 20 patients, matched for sex, age, and severity of hip OA, treated with high molecular weight hyaluronic acid.

The intra-group comparison showed a significant improvement in clinical and functional outcomes at three and six months in both cohorts, while the infra-group comparison showed better results in the patients treated with the study compound at six months (VAS at rest, P <0.04; VAS during activities, P <0.02; Harris Hip Score, P <0.001).

The present study is the first which demonstrates that a combination of low and high molecular weight HA is effective and safe in the management of patients suffering from hip OA and provides better therapeutic results in comparison to high molecular weight HA. We may infer that both HA preparations work synergically, enhancing their positive activities.

Bone Healing Improvements Using Hyaluronic Acid and Hydroxyapatite/Beta-Tricalcium Phosphate in Combination: An Animal Study

The purpose of this study was to investigate whether the use of HLA as an aqueous binder of hydroxyapatite/beta-tricalcium phosphate (HA-βTCP) particles can reduce the amount of bone graft needed and increase ease of handling in clinical situations. In this study, HA/βTCP was loaded in commercially available crosslinking HLA to form a novel HLA/HA-βTCP composite. Six New Zealand White rabbits (3.0-3.6 kg) were used as test subjects. Four 6 mm defects were prepared in the parietal bone. The defects were filled with the HLA/HA-βTCP composite as well as HA-βTCP particle alone. New bone formation was analyzed by micro-CT and histomorphometry. Our results indicated that even when the HA-βTCP particle numbers were reduced, the regenerative effect on bone remained when the HLA existed. The bone volume density (BV/TV ratio) of HLA/HA-βTCP samples was 1.7 times larger than that of the control sample at week 2. The new bone increasing ratio (NBIR) of HLA/HA-βTCP samples was 1.78 times higher than the control group at week 2. In conclusion, HA-βTCP powder with HLA contributed to bone healing in rabbit calvarial bone defects. The addition of HLA to bone grafts not only promoted osteoconduction but also improved handling characteristics in clinical situations.