Effects of laser irradiation on collagen organization in chemically induced degenerative annulus fibrosus of lumbar intervertebral disc

Application of a modified optical fiber in targeted percutaneous laser disc decompression of lumbar disc herniation: A retrospective study

Targeted percutaneous laser disc decompression (T-PLDD) is a minimally invasive technique for the treatment of lumbar disc herniation (LDH). However, the amount of energy required is large and the nerve can be easily damaged. Therefore, this technology requires improvement. The present study aimed to observe the effects of using a modified optical fiber (Mod) in T-PLDD for the treatment of LDH. A retrospective study was conducted using the database of the Affiliated Hospital of Qingdao University (Qingdao, China). In total, 58 patients who received T-PLDD with the Mod between June 2011 and May 2012 were included in the present study. The 10-point numeric rating score, pain rating index and good-to-excellent rating at 3 months (1.64±0.97; 5.79±1.57; 94.8%) were lower than those at 1 week (5.12±1.37; 11.52±1.85; 74.2%), and at 1 month (3.26±1.41; 7.83±1.31; 82.8%; P<0.05) and were maintained for up to 36 months (1.48±0.86; 4.91±1.43; 96.5%). The Oswestry disability index and 12-item Short Form Health Survey at 6 months (24.56±6.78; 69.40±5.08) were improved compared with 1 week, 1 month and 3 months, and were maintained for 36 months (23.10±6.20; 70.89±5.39). The T2 value decreased at 1 week (76±8) and returned to normal at 3 months (152±11). Additionally, patients in the Young group (<50 years old) recovered in a shorter period of time than the patients in the Elderly group. In conclusion, the patients stayed in hospital for 3.34±0.66 days; pain decreased and function increased optimally at 3–6 months and was maintained for 36 months with no serious complications. Individuals <50 years old may be more suitable candidates for T-PLDD with the Mod. The Mod should be applied and promoted in T-PLDD, and its use should be considered in the clinical setting.

Lasers in Spine Surgery

Laser spine surgery has been a focus of intense interest in the lay press and among patients. On the Internet, a host of purported benefits to laser surgery exists. Lasers have long been used in pain management procedures such as percutaneous diskectomy. However, a few published articles are available on lasers in conventional spine surgery. From our review of the literature, the purported advantages of lasers, such as reduced inflammation and degeneration, are not been supported by preclinical research. The available clinical studies do not show a notable advantage for laser surgery. Moreover, the low enrollment, nonblinded, retrospective studies that are available are heavily subject to bias. The documented advantages of laser spine surgery described in the research studies are not consistent with the public's impression of its purported benefits. Furthermore, laser-specific complications are present about which patients should be informed. On the basis of the current research, we conclude that lasers add distinct potential complications without any corresponding clinical benefit. Because of the public interest, we feel that this is an important topic for the general orthopaedic community.

Low Reactive Level Laser Therapy for Mesenchymal Stromal Cells Therapies

Low reactive level laser therapy (LLLT) is mainly focused on the activation of intracellular or extracellular chromophore and the initiation of cellular signaling by using low power lasers. Over the past forty years, it was realized that the laser therapy had the potential to improve wound healing and reduce pain and inflammation. In recent years, the term LLLT has become widely recognized in the field of regenerative medicine. In this review, we will describe the mechanisms of action of LLLT at a cellular level and introduce the application to mesenchymal stem cells and mesenchymal stromal cells (MSCs) therapies. Finally, our recent research results that LLLT enhanced the MSCs differentiation to osteoblast will also be described.

Effects of gamma irradiation on collagen damage and remodeling

PURPOSE

To evaluate the dose-time dependences of structural changes occurring in collagen within 24 hours to three months after gamma-irradiation at doses from 2-40 Gy in vivo.

MATERIALS AND METHODS

Rat's tail tendon was chosen as in vivo model, with its highly ordered collagen structure allowing the changes to be interpreted unambiguously. Macromolecular level (I) was investigated by differential scanning calorimetry (DSC); fibers and bundles level (II) by laser scanning microscopy (LSM), and bulk tissue microstructural level (III) by cross-polarization optical coherence tomography (CP-OCT).

RESULTS

For (I), the formation of molecular cross-links and breaks appeared to be a principal mechanism of collagen remodeling, with the cross-links number dependent on radiation dose. Changes on level (II) involved primary, secondary and tertiary bundles splitting in a day and a week after irradiation. Bulk collagen microstructure (III) demonstrated early widening of the interference fringes on CP-OCT images observed to occur in the tendon as result of this splitting. At all three levels, the observed collagen changes demonstrated complete remodeling within ∼ a month following irradiation.

CONCLUSION

The time course and dose dependencies of the observed collagen changes at different levels of its hierarchy further contribute to elucidating the role of connective tissue in the radiotherapy process.

Multimodal optical characterisation of collagen photodegradation by femtosecond infrared laser ablation

Collagen is a structural component of the human body, as a connective tissue it can become altered as a result of pathophysiological conditions. Although the collagen degradation mechanism is not fully understood, it plays an important role in ageing, disease progression and applications in therapeutic laser treatments. To fully understand the mechanism of collagen alteration, in our study photo-disruptive effects were induced in collagen I matrix by point-irradiation with a femtosecond Ti-sapphire laser under controlled laser ablation settings. This was followed by multi-modal imaging of the irradiated and surrounding areas to analyse the degradation mechanism. Our multi-modal methodology was based on second harmonic generation (SHG), scanning electron microscope (SEM), autofluorescence (AF) average intensities and the average fluorescence lifetime. This allowed us to quantitatively characterise the degraded area into four distinct zones: (1) depolymerised zone in the laser focal spot as indicated by the loss of SHG signal, (2) enhanced crosslinking zone in the inner boundary of the laser induced cavity as represented by the high fluorescence ring, (3) reduced crosslinking zone formed the outer boundary of the cavity as marked by the increased SHG signal and (4) native collagen. These identified distinct zones were in good agreement with the expected photochemical changes shown using Raman spectroscopy. In addition, imaging using polarisation-resolved SHG (p-SHG) revealed both a high degree of fibre re-orientation and a SHG change in tensor ratios around the irradiation spot. Our multi-modal optical imaging approach can provide a new methodology for defining distinct zones that can be used in a clinical setting to determine suitable thresholds for applying safe laser treatments without affecting the surrounding tissues. Furthermore this technique can be extended to address challenges observed in collagen based tissue engineering and used as a minimally invasive diagnostic tool to characterise diseased and non-diseased collagen rich tissues.

Biomechanical and biochemical protective effect of low-level laser therapy for Achilles tendinitis

For three decades, low level laser therapy (LLLT) has been used for treatment of tendinitis as well as other musculoskeletal diseases. Nevertheless, the biological mechanisms involved remain not completely understood. In this work, the effects of LLLT and of the widely used nonsteroidal anti-inflammatory drug, diclofenac, have been compared in the case of collagenase-induced Achilles tendinitis. Wistar rats were treated with diclofenac or laser therapy. The tensile behavior of tendons was characterized through successive loading-unloading sequences. The method considered 11 characteristic parameters to describe the mechanical behavior. It was shown that during the acute inflammatory process of the tendon, the mechanical properties were significantly correlated to the high levels of MMP-3, MMP-9 and MMP-13 expression presented in a previous paper (Marcos, R.L., et al., 2012). The treatment by non-steroidal anti-inflammatory drugs such as diclofenac sodium produces a low protective effect and can affect the short-term biochemical and biomechanical properties. On the contrary, it is shown that LLLT exhibits the best results in terms of MMPs reduction and mechanical properties recovery. Thus, LLLT looks to be a promising and consistent treatment for tendinopathies.

Regulation of miRNA expression by low-level laser therapy (LLLT) and photodynamic therapy (PDT)

Applications of laser therapy, including low-level laser therapy (LLLT), phototherapy and photodynamic therapy (PDT), have been proven to be beneficial and relatively less invasive therapeutic modalities for numerous diseases and disease conditions. Using specific types of laser irradiation, specific cellular activities can be induced. Because multiple cellular signaling cascades are simultaneously activated in cells exposed to lasers, understanding the molecular responses within cells will aid in the development of laser therapies. In order to understand in detail the molecular mechanisms of LLLT and PDT-related responses, it will be useful to characterize the specific expression of miRNAs and proteins. Such analyses will provide an important source for new applications of laser therapy, as well as for the development of individualized treatments. Although several miRNAs should be up- or down-regulated upon stimulation by LLLT, phototherapy and PDT, very few published studies address the effect of laser therapy on miRNA expression. In this review, we focus on LLLT, phototherapy and PDT as representative laser therapies and discuss the effects of these therapies on miRNA expression.

Effects of low-level laser irradiation on proliferation and osteoblastic differentiation of human mesenchymal stem cells seeded on a three-dimensional biomatrix: in vitro pilot study

Mesenchymal stem cells (MSCs) from bone marrow are a recent source for tissue engineering. Several studies have shown that low-level laser irradiation has numerous biostimulating effects. The purpose of this trial was to evaluate the effects of Nd:Yag laser irradiation on proliferation and differentiation of MSCs induced into the osteoblastic lineage. MSCs were collected from adult human bone marrow, isolated, and cultured in complete medium (α-MEM). Subsequently, they were treated with osteogenic medium, seeded in three-dimensional collagen scaffolds, and incubated. We used six scaffolds, equally divided into three groups: two of these were irradiated with Nd:Yag laser at different power levels (15 Hz, 100 mJ, 1.5 W, and one with a power level of 15 Hz, 150 mJ, 2.25 W), and one was left untreated (control group). Evaluations with specific staining were performed at 7 and 14 days. After 7 days, proliferation was significantly increased in scaffolds treated with laser, compared with the control scaffold. After 14 days, however, laser irradiation did not appear to have any further effect on cell proliferation. As concerns differentiation, an exponential increase was observed after 14 days of laser irradiation, with respect to the control group. However, this was a pilot study with very limited sample size, we conclude, that low-level laser irradiation might lead to a reduction in healing times and potentially reduces risks of failure.

Lasers, stem cells, and COPD

The medical use of low level laser (LLL) irradiation has been occurring for decades, primarily in the area of tissue healing and inflammatory conditions. Despite little mechanistic knowledge, the concept of a non-invasive, non-thermal intervention that has the potential to modulate regenerative processes is worthy of attention when searching for novel methods of augmenting stem cell-based therapies. Here we discuss the use of LLL irradiation as a "photoceutical" for enhancing production of stem cell growth/chemoattractant factors, stimulation of angiogenesis, and directly augmenting proliferation of stem cells. The combination of LLL together with allogeneic and autologous stem cells, as well as post-mobilization directing of stem cells will be discussed.