Effects of high antibiotic concentrations applied to continuous local antibiotic perfusion on human bone tissue-derived cells.

Aims: Continuous local antibiotic perfusion (CLAP) has recently attracted attention as a new drug delivery system for orthopaedic infections. CLAP is a direct continuous infusion of high-concentration gentamicin (1,200 µg/ml) into the bone marrow. As it is a new system, its influence on the bone marrow is unknown. This study aimed to examine the effects of high-concentration antibiotics on human bone tissue-derived cells. Methods: Cells were isolated from the bone tissue grafts collected from six patients using the Reamer-Irrigator-Aspirator system, and exposed to different gentamicin concentrations. Live cells rate, apoptosis rate, alkaline phosphatase (ALP) activity, expression of osteoblast-related genes, mineralization potential, and restoration of cell viability and ALP activity were examined by in vitro studies. Results: The live cells rate (the ratio of total number of cells in the well plate to the absorbance-measured number of live cells) was significantly decreased at ≥ 500 µg/ml of gentamicin on day 14; apoptosis rate was significantly increased at ≥ 750 µg/ml, and ALP activity was significantly decreased at ≥ 750 µg/ml. Real-time reverse transcription-polymerase chain reaction results showed no significant decrease in the ALP and activating transcription factor 4 transcript levels at ≥ 1,000 µg/ml on day 7. Mineralization potential was significantly decreased at all concentrations. Restoration of cell viability was significantly decreased at 750 and 1,000 µg/ml on day 21 and at 500 µg/ml on day 28, and ALP activity was significantly decreased at 500 µg/ml on day 28. Conclusion: Our findings suggest that the exposure concentration and duration of antibiotic administration during CLAP could affect cell functions. However, further in vivo studies are needed to determine the optimal dose in a clinical setting.

Effect of low-intensity pulsed ultrasound on osteogenic differentiation of human induced membrane-derived cells in Masquelet technique.

INTRODUCTION: The Masquelet technique is a relatively new method for large bone defect treatment. In this technique, grafted bone tissue is used, and after the cement is removed, the induced membrane (IM; that form around the cement spacers placed in the bone defect region) is thought to play an important role in promoting bone formation. On the other hand, low-intensity pulsed ultrasound (LIPUS) is known to promote fracture healing and angiogenesis through mechanical stimulation. This study aimed to investigate the in vitro effects of LIPUS on the osteogenic differentiation of human induced membrane-derived cells (IMCs). METHODS: Seven patients who had been treated using the Masquelet technique were enrolled. The IM was harvested during the second stage of the technique. IMCs were isolated, cultured in growth medium, and then divided into two groups: (1) control group, IMCs cultured in osteogenic medium without LIPUS, and (2) LIPUS group, IMCs cultured in osteogenic medium with LIPUS treatment. Adherent cells from the IM samples were harvested after the first passage and evaluated for cell surface protein expression using immunostaining. A cell proliferation assay was used to count the number of IMCs using a hemocytometer. Osteogenic differentiation capability was assessed using an alkaline phosphatase (ALP) activity assay, Alizarin Red S staining, and real-time reverse transcription-polymerase chain reaction. RESULTS: Cell surface antigen profiling revealed that the IMCs contained cells positive for the mesenchymal stem cell-related markers CD73, CD90, and CD105. No significant difference in cell numbers was found between the control and LIPUS groups. The ALP activity of IMCs in the LIPUS group was significantly higher than that in the control group on days 7 and 14. Alizarin red S staining intensity was significantly higher in the LIPUS group than in the control group on day 21. Runx2 and VEGF expression was significantly upregulated on days 7 and 14, respectively, compared with levels in the control group. CONCLUSION: We demonstrated the significant effect of LIPUS on the osteogenic differentiation of human IMCs. This study indicates that LIPUS can be used as an additional tool for the enhancement of the healing process of the Masquelet technique.

Human Non-Hypertrophic Nonunion Tissue Contains Osteoblast Lineage Cells and E-BMP-2 Activates Osteogenic and Chondrogenic Differentiation.

In this study, we examined the proliferation capability and osteogenic and chondrogenic differentiation potential of non-hypertrophic nonunion cells (NHNCs), and the effect of Escherichia coli-derived BMP-2 (E-BMP-2) on them. We enrolled five patients with non-hypertrophic nonunion. NHNCs isolated from nonunion tissue sampled during surgery were cultured, passaged, counted every 14 days, and analyzed. NHNCs were homogenous fibroblastic adherent cells and long-lived through at least 10 passages, with a slight decline. The cells were consistently positive for mesenchymal stem cell-related markers CD73 and CD105, and negative for the hematopoietic markers CD14 and CD45. NHNCs could differentiate into osteoblast lineage cells; however, they did not have strong calcification or sufficient chondrogenic differentiation capability. E-BMP-2 did not affect the proliferative capability of the cells but improved their osteogenic differentiation capability by increasing alkaline phosphatase activity and upregulating the gene expression of osterix, bone sialoprotein, and osteocalcin. E-BMP-2 enhanced their chondrogenic differentiation capability by upregulating the gene expression of aggrecan and collagen type II. We showed, for the first time, that NHNCs have the capacity to differentiate into osteoblast-lineage cells, although the chondrogenic differentiation potential was poor. Local application of E-BMP-2 with preservation of nonunion tissue is a potential treatment option for non-hypertrophic nonunion.

Low-Intensity Pulsed Ultrasound Promotes Osteogenic Differentiation of Reamer-Irrigator-Aspirator Graft-Derived Cells in Vitro.

Recently, reamer-irrigator-aspirator (RIA) systems have been increasingly used to harvest autologous bone grafts. RIA graft materials contain bone marrow, which provides a viable source to derive large numbers of mesenchymal stem cells. Low-intensity pulsed ultrasound (LIPUS) significantly accelerates the differentiation of stem cells derived from bone marrow. This in vitro study investigated the effect of LIPUS on the osteogenic activity and differentiation of RIA graft-derived cells. A small amount of RIA graft was obtained from seven patients. After the cells derived from RIA grafts were cultured, they were divided into two groups: the LIPUS and control groups. LIPUS was applied once daily for 20 min (1.5 MHz, pulse duration: 200 µs, pulse repetition rate: 1 kHz, spatial average-temporal average intensity: 30 mW/cm2). Alkaline phosphatase activity (113.4% and 130.1% on days 7 and 14), expression of osteoblast-related genes (ALP, Runx2) and mineralization (135.2% on day 21) of the RIA graft-derived cells were significantly higher in the LIPUS group than in the control group. However, LIPUS did not affect the cell proliferation of RIA graft-derived cells. This study indicates that LIPUS may enhance the healing of non-union and critical bone defects treated by autologous bone grafting using the RIA system.

Second-look arthroscopic findings of cartilage and meniscus repair after injection of adipose-derived regenerative cells in knee osteoarthrits: Report of two cases.

BACKGROUND: The purpose of this study was to use second-look arthroscopic findings and clinical assessment to determine outcome in two cases of knee osteoarthritis treated by intra-articular knee injection of adipose-derived regenerative cells (ADRCs). CASE PRESENTATION: This study involved two patients who received ADRC therapy for knee osteoarthritis and completed the six-month post-treatment follow-up period. For each treatment, 130 mL of subcutaneous adipose tissue was harvested using tumescent liposuction technique and manual aspiration of tissue from the thigh using a suction cannula under local anesthesia in the operating room. The adipose tissue harvested was processed using the Celution® Centrifuge in a dedicated cell processing room. The ADRCs were injected into the articular cavity of both knees for one patient and into a single affected knee in the second patient (three joints). Pain and knee function were assessed using a Visual Analogue Scale (VAS) and the Knee Outcome in Osteoarthritis Score (KOOS) respectively. The cartilage defect was assessed by direct visualization (arthroscopy). No serious adverse events were reported throughout follow-up. Pain and knee function were significantly improved from baseline in all treated knees at one, three and six months after ADRCs. At six-months after ADRCs treatment, the second-look arthroscopy showed that almost all the cartilage defect areas were covered by regenerated cartilage, some cartilage fibrillation area was reduced, and meniscus tear areas were repaired. CONCLUSIONS: Cartilage and meniscus repair were observed six-months after ADRCs therapy under second-look arthroscopy. It was shown that a single administration of ADRCs might be effective as a treatment for knee osteoarthritis.

Minimally Invasive Treatment for Tibial Malrotation after Locked Intramedullary Nailing.

Rotational malreduction is a potential complication of intramedullary nailing for tibial shaft fractures. We experienced a symptomatic case of a 24° externally rotated malunion that we treated with minimally invasive corrective osteotomy. A 49-year-old man sustained a tibial shaft spiral fracture with a fibula fracture. He had been initially treated elsewhere with a reamed statically locked intramedullary nail. Bone union had been obtained, but he complained of asymmetry of his legs, difficulty walking and running, and the inability to ride a bicycle. We decided to perform corrective osteotomy in a minimally invasive fashion. After a 1 cm incision was made at the original fracture site, osteotomy for the affected tibia was performed with an osteotome after multiple efforts at drilling around the nail with the aim of retaining it. Fibula osteotomy was also performed at the same level. Two Kirschner wires that created an affected rotational angle between the fragments were inserted as a guide for correction. The distal locking screws were removed. Correct rotation was regained by matching the two wires in a straight line. Finally, the distal locking screws were inserted into new holes. The patient obtained bony union and has returned to his preinjury activities with no symptoms.