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Yaron JR, Gosangi M, Pallod S, Rege K. In situ light-activated materials for skin wound healing and repair: A narrative review. Bioeng Transl Med 2024; 9:e10637. [PMID: 38818119 PMCID: PMC11135152 DOI: 10.1002/btm2.10637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 11/22/2023] [Accepted: 12/12/2023] [Indexed: 06/01/2024] Open
Abstract
Dermal wounds are a major global health burden made worse by common comorbidities such as diabetes and infection. Appropriate wound closure relies on a highly coordinated series of cellular events, ultimately bridging tissue gaps and regenerating normal physiological structures. Wound dressings are an important component of wound care management, providing a barrier against external insults while preserving the active reparative processes underway within the wound bed. The development of wound dressings with biomaterial constituents has become an attractive design strategy due to the varied functions intrinsic in biological polymers, such as cell instructiveness, growth factor binding, antimicrobial properties, and tissue integration. Using photosensitive agents to generate crosslinked or photopolymerized dressings in situ provides an opportunity to develop dressings rapidly within the wound bed, facilitating robust adhesion to the wound bed for greater barrier protection and adaptation to irregular wound shapes. Despite the popularity of this fabrication approach, relatively few experimental wound dressings have undergone preclinical translation into animal models, limiting the overall integrity of assessing their potential as effective wound dressings. Here, we provide an up-to-date narrative review of reported photoinitiator- and wavelength-guided design strategies for in situ light activation of biomaterial dressings that have been evaluated in preclinical wound healing models.
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Affiliation(s)
- Jordan R. Yaron
- Center for Biomaterials Innovation and Translation, The Biodesign Institute, Arizona State UniversityTempeArizonaUSA
- School for Engineering of Matter, Transport, and Energy, Ira A. Fulton Schools of Engineering, Arizona State UniversityTempeArizonaUSA
| | - Mallikarjun Gosangi
- Center for Biomaterials Innovation and Translation, The Biodesign Institute, Arizona State UniversityTempeArizonaUSA
| | - Shubham Pallod
- Center for Biomaterials Innovation and Translation, The Biodesign Institute, Arizona State UniversityTempeArizonaUSA
| | - Kaushal Rege
- Center for Biomaterials Innovation and Translation, The Biodesign Institute, Arizona State UniversityTempeArizonaUSA
- School for Engineering of Matter, Transport, and Energy, Ira A. Fulton Schools of Engineering, Arizona State UniversityTempeArizonaUSA
- Chemical Engineering, Arizona State UniversityTempeArizonaUSA
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Thomas S, Sriramoju V, Alfano RR. Laser tissue welding by using collagen excitation at a 1,720 nm near-infrared optical window III. APPLIED OPTICS 2024; 63:1007-1014. [PMID: 38437398 DOI: 10.1364/ao.500113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 11/20/2023] [Indexed: 03/06/2024]
Abstract
Laser tissue welding (LTW) is a method of fusing incised tissues together. LTW has the potential to revolutionize plastic surgery and wound healing techniques by its ability to produce watertight, scarless seals with minimal foreign body reaction. While using thermal mechanisms to achieve LTW, energy from the incident laser is absorbed by water in the tissue. As the water temperature increases, partial denaturing of the collagen triple helix briefly occurs, which is quickly followed by renaturation of collagen as the tissue cools, thus providing a watertight seal. This research study investigates the efficacy of direct collagen excitation at 1,720 nm to accomplish LTW. This wavelength falls within the near-infrared (NIR) optical window III. The tensile strengths of pig skin that have been welded with NIR continuous-wave (CW) diode lasers at 1,455 nm, which promote thermal mechanisms of tissue welding, and 1,720 nm wavelengths, are compared. Near-infrared lasers tuned to 1,455 and 1,720 nm were used to weld incised pieces of porcine skin together without extrinsic solders or dyes. The tensile force of the welded tissues was measured using a digital force gauge. The average tensile force of the welded pig skin using the 1,720 nm laser was approximately four times greater than that using the CW 1,455 nm laser, suggesting that LTW accomplished through direct collagen excitation in the NIR optical window III provides greater tensile strengths.
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Interdisciplinary Methods for Zoonotic Tissue Acellularization for Natural Heart Valve Substitute of Biomimetic Materials. MATERIALS 2022; 15:ma15072594. [PMID: 35407927 PMCID: PMC9000896 DOI: 10.3390/ma15072594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/14/2022] [Accepted: 03/29/2022] [Indexed: 02/04/2023]
Abstract
The goal of this work was to create a bioactive tissue-based scaffold using multi-disciplinary engineering materials and tissue engineering techniques. Materials & methods: Physical techniques such as direct laser interference lithography and proton radiation were selected as alternative methods of enzymatic and chemical decellularization to remove cells from a tissue without degradation of the extracellular matrix nor its protein structure. This study was an attempt to prepare a functional scaffold for cell culture from tissue of animal origin using new physical methods that have not been considered before. The work was carried out under full control of the histological and molecular analysis. Results & conclusions: The most important finding was that the physical methods used to obtain the decellularized tissue scaffold differed in the efficiency of cell removal from the tissue in favour of the laser method. Both the laser method and the proton method exhibited a destructive effect on tissue structure and the genetic material in cell nuclei. This effect was visible on histology images as blurred areas within the cell nucleus. The finite element 3D simulation of decellularization process of the three-layer tissue of animal origin sample reflected well the mechanical response of tissue described by hyperelastic material models and provided results comparable to the experimental ones.
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Litvinova K, Chernysheva M, Stegemann B, Leyva F. Autofluorescence guided welding of heart tissue by laser pulse bursts at 1550 nm. BIOMEDICAL OPTICS EXPRESS 2020; 11:6271-6280. [PMID: 33282489 PMCID: PMC7687929 DOI: 10.1364/boe.400504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/30/2020] [Accepted: 10/06/2020] [Indexed: 06/12/2023]
Abstract
Wound healing and other surgical technologies traditionally solved by suturing and stapling have recently been enhanced by the application of laser tissue welding. The usage of high energy laser radiation to anastomose tissues eliminates a foreign body reaction, reduces scar formation, and allows for the creation of watertight closure. In the current work, we show that an ultrafast pulsed fibre laser beam with 183 µJ·cm-2 energy fluence at 1550 nm provides successful welding of dissected chicken heart walls with the tensile strength of 1.03±0.12 kg·cm-2 equal to that of native tissue. The welding process was monitored employing fluorescence spectroscopy that detects the biochemical composition of tissues. We believe that fluorescence spectroscopy guided laser tissue welding is a promising approach for decreasing wound healing times and the avoiding risks of postoperative complications.
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Affiliation(s)
- Karina Litvinova
- Aston Medical School, Aston University, Aston Triangle, B4 7ET, Birmingham, UK
| | - Maria Chernysheva
- Leibniz Institute of Photonic Technology, Albert Einstein str 9, 07745, Jena, Germany
| | - Berthold Stegemann
- Aston Medical School, Aston University, Aston Triangle, B4 7ET, Birmingham, UK
| | - Francisco Leyva
- Aston Medical School, Aston University, Aston Triangle, B4 7ET, Birmingham, UK
- Cardiology Department, Queen Elizabeth Hospital, Mindelsohn Way, B15 2TH, Birmingham, UK
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Kramer EA, Rentschler ME. Energy-Based Tissue Fusion for Sutureless Closure: Applications, Mechanisms, and Potential for Functional Recovery. Annu Rev Biomed Eng 2019; 20:1-20. [PMID: 29865874 DOI: 10.1146/annurev-bioeng-071516-044702] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
As minimally invasive surgical techniques progress, the demand for efficient, reliable methods for vascular ligation and tissue closure becomes pronounced. The surgical advantages of energy-based vessel sealing exceed those of traditional, compression-based ligatures in procedures sensitive to duration, foreign bodies, and recovery time alike. Although the use of energy-based devices to seal or transect vasculature and connective tissue bundles is widespread, the breadth of heating strategies and energy dosimetry used across devices underscores an uncertainty as to the molecular nature of the sealing mechanism and induced tissue effect. Furthermore, energy-based techniques exhibit promise for the closure and functional repair of soft and connective tissues in the nervous, enteral, and dermal tissue domains. A constitutive theory of molecular bonding forces that arise in response to supraphysiological temperatures is required in order to optimize and progress the use of energy-based tissue fusion. While rapid tissue bonding has been suggested to arise from dehydration, dipole interactions, molecular cross-links, or the coagulation of cellular proteins, long-term functional tissue repair across fusion boundaries requires that the reaction to thermal damage be tailored to catalyze the onset of biological healing and remodeling. In this review, we compile and contrast findings from published thermal fusion research in an effort to encourage a molecular approach to characterization of the prevalent and promising energy-based tissue bond.
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Affiliation(s)
- Eric A Kramer
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA;
| | - Mark E Rentschler
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA; .,Departments of Surgery and Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
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Li K, Nicoli F, Xi WJ, Zhang Z, Cui C, Al-Mousawi A, Balzani A, Tong Y, Zhang Y. The 1470 nm diode laser with an intralesional fiber device: a proposed solution for the treatment of inflamed and infected keloids. BURNS & TRAUMA 2019; 7:5. [PMID: 30783604 PMCID: PMC6376646 DOI: 10.1186/s41038-019-0143-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 01/21/2019] [Indexed: 01/08/2023]
Abstract
Background Keloids are the result of abnormal wound healing and often are subject to infections and recurrent inflammation. We present a study conducted with a 1470 nm diode laser using an intralesional optical fiber device for the treatment of inflamed keloid scars. We evaluate its efficacy as a novel alternative method to decrease keloid infection and inflammation. Methods The patients who underwent 1470 nm laser treatment from February 2016 to February 2018 at the plastic and reconstructive surgery department of the Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University with keloid accompanying serious local infection and fester were included. Patients took curative effect evaluation before and 1 year after the treatment. The test items included infection frequency in each year; pain, by visual analogue scale (VAS); itch, using VAS; quality of life (QOL), using QOL scale; and blood supply, using PeriCam PSI. Results A total of 19 patients (mean age 35.21 years, range 11–66) with history of inflamed keloids with episodes of infection or abscess were enrolled. Patients underwent to a 1470 nm laser therapy for average of 1.16 times. After treatment, infection frequency and blood supply in keloids were reduced (p < 0.001). Pain, itching, and QOL were improved (p < 0.001). Conclusion The present study shows that 1470 nm fiber laser treatment could improve inflamed keloids fairly well by decreasing inflammation, and a relative stabilization of collagen composition. Therefore, it is an effective minimally invasive scar therapy, but further studies are essential to confirm the present results.
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Affiliation(s)
- Ke Li
- 1Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhi Zao Ju Road, Shanghai, 200011 China
| | - Fabio Nicoli
- 2Department of Plastic and Reconstructive Surgery, University of Rome "Tor Vergata", Rome, Italy.,3Department of Plastic and Reconstructive Surgery, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Wen Jing Xi
- 1Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhi Zao Ju Road, Shanghai, 200011 China
| | - Zheng Zhang
- 1Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhi Zao Ju Road, Shanghai, 200011 China
| | - Chunxiao Cui
- 1Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhi Zao Ju Road, Shanghai, 200011 China
| | - Ahmed Al-Mousawi
- 3Department of Plastic and Reconstructive Surgery, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Alberto Balzani
- 2Department of Plastic and Reconstructive Surgery, University of Rome "Tor Vergata", Rome, Italy
| | - Yun Tong
- Department of Medical Cosmetology Surgery, Jinhua People's Hospital, Jinhua, China
| | - Yixin Zhang
- 1Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhi Zao Ju Road, Shanghai, 200011 China
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Alfano RR, Wang WB, Wang L, Gayen SK. Light Propagation in Highly Scattering Turbid Media: Concepts, Techniques, and Biomedical Applications. PHOTONICS 2015. [DOI: 10.1002/9781119011804.ch9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Xu N, Yao M, Farinelli W, Hajjarian Z, Wang Y, Redmond RW, Kochevar IE. Light-activated sealing of skin wounds. Lasers Surg Med 2014; 47:17-29. [PMID: 25418831 DOI: 10.1002/lsm.22308] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2014] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND OBJECTIVES We have developed a light-activated technology for rapidly sealing skin surgical wounds called photochemical tissue bonding (PTB). The goals of this study were to evaluate parameters influencing PTB in order to optimize its clinical efficacy and to determine whether PTB can be used to seal wounds in moderately to highly pigmented skin. STUDY DESIGN/MATERIALS AND METHODS Application of Rose Bengal (RB) followed by exposure to 532 nm was used to seal linear incisions (1.5 mm deep, 2 cm long) in lightly pigmented (Yorkshire) and darkly pigmented (Yucatan) swine skin. The force required to open the seal (the bonding strength) was measured by in situ tensiometry. Reflectance spectra, epidermal transmission spectra, and histology were used to characterize the skin. The relationships of RB concentration and fluence to bonding strength were established in Yorkshire skin. Surface temperature was measured during irradiations and cooling was used while sealing incisions in Yucatan skin. Monte Carlo simulations were carried out to estimate the effect of epidermal melanin on the power absorbed in the dermis at the incision interface. RESULTS The lowest fluence, 25 J/cm(2), delivered at an irradiance of 0.5 W/cm(2) substantially increased the bonding strength (∼ 10-fold) compared to controls in Yorkshire swine skin. Increasing the fluence to 100 J/cm(2) enhanced bonding strength by a further 1.5-fold. Application of 0.1% RB for 2 minutes produced the greatest bonding strength using 100 J/cm(2) and limited the penetration of RB to an ∼ 50 μm band on the dermal incision wall. Reflectance spectra indicated that Yorkshire skin had minimal melanin and that Yucatan skin was a good model for highly pigmented human skin. In Yucatan skin, the bonding strength increased 1.7-fold using 0.1% RB and 200 J/cm(2) at 1.5 W/cm(2) with cooling and epinephrine. Monte Carlo simulation indicated that absorption of 532 nm light by epidermal melanin in dark skin decreased the power absorbed along the incision in the dermis by a factor of 2.7. CONCLUSIONS These results suggest that in lightly pigmented skin the PTB treatment time can be shortened without compromising the bonding strength. Sealing incisions using PTB in moderately and highly pigmented skin will require a careful balance of irradiance and cooling.
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Affiliation(s)
- Nan Xu
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Dermatology Department, Shanghai East Hospital, Tongji University, Shanghai, China
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Rasca E, Nyssen-Behets C, Tielemans M, Peremans A, Hendaoui N, Heysselaer D, Romeo U, Nammour S. Gingiva laser welding: preliminary study on an ex vivo porcine model. Photomed Laser Surg 2014; 32:437-43. [PMID: 25014573 DOI: 10.1089/pho.2013.3662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE The use of lasers to fuse different tissues has been studied for 50 years. As none of these experiments concerned the oral soft tissues, our objective was to assess the feasibility of laser gingiva welding. MATERIALS AND METHODS Porcine full-thickness gingival flaps served to prepare calibrated samples in the middle of which a 2 cm long incision was closed, either by conventional suture or by laser tissue welding (LTW). To determine the irradiation conditions yielding the best tensile strength, 13 output power values, from 0.5 to 5 W, delivered either at 10 Hz or in continuous wave mode, were tested on six indocyanine green (ICG) concentrations, from 8% to 13% (588 samples). Then, some samples served to compare the tensile strength between the laser welded and the sutured gingiva; the other samples were histologically processed in order to evaluate the thermal damage extent. The temperature rise during the LTW was measured by thermocouples. Another group of 12 samples was used to measure the temperature elevation by thermal camera. RESULTS In the laser welding groups, the best tensile strength (p<0.05) was yielded by the 9% ICG saline solution (117 mM) at 4.5 W, 10 Hz, and a fluence of 31.3 kJ/cm(2). The apposition strength revealed no statistically significant difference (p<0.05) between the sutured and the laser welded gingiva at 4.5 W, 10 Hz, and 9% ICG solution. The mean temperature was 74±5.4°C at the upper surface and 42±8.9°C at the lower surface. The damaged zone averaged 333 μm at the upper surface. CONCLUSIONS The 808 nm diode laser associated with ICG can achieve oral mucosa LTW, which is conceivable as a promising technique of gingival repair.
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Affiliation(s)
- Emilia Rasca
- 1 Department of Dental Sciences, Faculty of Medicine, University of Liège , Liège, Belgium
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Sriramoju V, Alfano RR. Laser tissue welding analyzed using fluorescence, Stokes shift spectroscopy, and Huang-Rhys parameter. JOURNAL OF BIOPHOTONICS 2012; 5:185-193. [PMID: 22076914 DOI: 10.1002/jbio.201100050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Revised: 09/27/2011] [Accepted: 09/28/2011] [Indexed: 05/31/2023]
Abstract
Near infrared (NIR) continuous wave laser radiation at the 1,450 nm wavelength was used to weld porcine aorta and skin samples via the absorption of combitional vibrational modes of native water in the tissues. The fluorescence spectra were measured from the key native molecules of welded and non-welded tissues at specific excitation and emission wavelengths from collagen, elastin, and tryptophan. The changes in the fluorescence intensities and differences in Stokes shift (Δν(ss) ) of key native fluorophores were measured to differentiate the Huang-Rhys parameter values (S) of the chromophores. The strength of coupling depends on the local electron-vibration intra-tissue molecular environment and the amount of polar solvent water surrounding the net charges on collagen, elastin, and tryptophan. The S values for both non-welded and welded tissues were almost the same and less than 3, suggesting minimal changes in the local molecular environment as a result of welding.
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Affiliation(s)
- Vidyasagar Sriramoju
- Institute for Ultrafast Spectroscopy and Lasers, Department of Physics, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
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Prabhu V, Rao SBS, Chandra S, Kumar P, Rao L, Guddattu V, Satyamoorthy K, Mahato KK. Spectroscopic and histological evaluation of wound healing progression following Low Level Laser Therapy (LLLT). JOURNAL OF BIOPHOTONICS 2012; 5:168-84. [PMID: 22174176 DOI: 10.1002/jbio.201100089] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 11/23/2011] [Accepted: 11/23/2011] [Indexed: 05/09/2023]
Abstract
The present study focuses on the evaluation of the effect of He-Ne laser on tissue regeneration by monitoring collagen synthesis in wound granulation tissues in Swiss albino mice using analysis of laser induced fluorescence (LIF) and light microscopy techniques. The spectral analyses of the wound granulation tissues have indicated a dose dependent increase in collagen levels during the post-wounding days. The histological examinations on the other hand have also shown a significant increase in collagen deposition along with the reduced edema, leukocytes, increased granulation tissue, and fibroblast number in the optimal laser dose treated group compared to the non-illuminated controls.
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Affiliation(s)
- Vijendra Prabhu
- Biophysics Unit, Manipal Life Sciences Centre, Manipal University, Manipal 576104, Karnataka, India
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Sriramoju V, Alfano RR. Management of heat in laser tissue welding using NIR cover window material. Lasers Surg Med 2011; 43:991-7. [DOI: 10.1002/lsm.21143] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2011] [Indexed: 11/06/2022]
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Khosroshahi M, Nourbakhsh MS. In vitro skin wound soldering using SiO2/Au nanoshells and a diode laser. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.mla.2010.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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An in-vitro investigation of skin tissue soldering using gold nanoshells and diode laser. Lasers Med Sci 2010; 26:49-55. [DOI: 10.1007/s10103-010-0805-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 06/09/2010] [Indexed: 10/19/2022]
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In vivo molecular evaluation of guinea pig skin incisions healing after surgical suture and laser tissue welding using Raman spectroscopy. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2009; 96:178-83. [PMID: 19581109 DOI: 10.1016/j.jphotobiol.2009.06.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 06/09/2009] [Accepted: 06/10/2009] [Indexed: 11/24/2022]
Abstract
The healing process in guinea pig skin following surgical incisions was evaluated at the molecular level, in vivo, by the use of Raman spectroscopy. After the incisions were closed either by suturing or by laser tissue welding (LTW), differences in the respective Raman spectra were identified. The study determined that the ratio of the Raman peaks of the amide III (1247 cm(-1)) band to a peak at 1326 cm(-1) (the superposition of elastin and keratin bands) can be used to evaluate the progression of wound healing. Conformational changes in the amide I band (1633-1682 cm(-1)) and spectrum changes in the range of 1450-1520 cm(-1) were observed in LTW and sutured skin. The stages of the healing process of the guinea pig skin following LTW and suturing were evaluated by Raman spectroscopy, using histopathology as the gold standard. LTW skin demonstrated better healing than sutured skin, exhibiting minimal hyperkeratosis, minimal collagen deposition, near-normal surface contour, and minimal loss of dermal appendages. A wavelet decomposition-reconstruction baseline correction algorithm was employed to remove the fluorescence wing from the Raman spectra.
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Matteini P, Rossi F, Menabuoni L, Pini R. Microscopic characterization of collagen modifications induced by low-temperature diode-laser welding of corneal tissue. Lasers Surg Med 2007; 39:597-604. [PMID: 17868101 DOI: 10.1002/lsm.20532] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVE Laser welding of corneal tissue that employs diode lasers (810 nm) at low power densities (12-20 W/cm(2)) in association with Indocyanine Green staining of the wound is a technique proposed as an alternative to conventional suturing procedures. The aim of this study is to evaluate, by means of light (LM) and transmission electron microscopy (TEM) analyses, the structural modifications induced in laser-welded corneal stroma. MATERIALS AND METHODS Experiments were carried out in 20 freshly enucleated pig eyes. A 3.5 mm in length full-thickness cut was produced in the cornea, and was then closed by laser welding. Birefringence modifications in samples stained with picrosirius red dye were analyzed by polarized LM to assess heat damage. TEM analysis was performed on ultra-thin slices, contrasted with uranyl acetate and lead citrate, in order to assess organization and size of type I collagen fibrils after laser welding. RESULTS LM evidenced bridges of collagen bundles between the wound edges, with a loss of regular lamellar organization at the welded site. Polarized LM indicated that birefringence properties were mostly preserved after laser treatment. TEM examinations revealed the presence of quasi-ordered groups of fibrils across the wound edges preserving their interfibrillar spacing. These fibrils appeared morphologically comparable to those in the control tissue, indicating that type I collagen was not denatured during the diode laser corneal welding. CONCLUSIONS The preservation of substantially intact, undenatured collagen fibrils in laser-welded corneal wounds supported the thermodynamic studies that we carried out recently, which indicated temperatures below 66 degrees C at the weld site under laser irradiation. This observation enabled us to hypothesize that the mechanism, proposed in the literature, of unwinding of collagen triple helixes followed by fibrils "interdigitation" is not likely to occur in the welding process that we set up for the corneal suturing.
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Affiliation(s)
- Paolo Matteini
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata Nello Carrara, Sesto Fiorentino, Italy
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Kamegaya Y, Farinelli WA, Vila Echague AV, Akita H, Gallagher J, Flotte TJ, Anderson RR, Redmond RW, Kochevar IE. Evaluation of photochemical tissue bonding for closure of skin incisions and excisions. Lasers Surg Med 2005; 37:264-70. [PMID: 16196042 DOI: 10.1002/lsm.20221] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND AND OBJECTIVES Photochemical tissue bonding (PTB) is a new non-thermal technique for tissue repair involving application of a photochemically active dye and irradiation with visible light. The objective was to compare PTB with standard sutures and the tissue adhesive, octyl cyanoacrylate, for closure of skin incisions and excisions. STUDY DESIGN/MATERIALS AND METHODS Incisions and excisions made on the flanks of a Hanford mini-pig were secured with subcutaneous sutures. Superficial closure methods were 3-0 monofilament sutures, PTB (Rose Bengal and green light), tissue adhesive and the combination of tissue adhesive then PTB. Wounds were evaluated 2, 4, and 6 weeks postoperatively for cosmetic outcomes and histology. RESULTS Cosmetic outcomes and histological scar width of incisions and excisions did not differ among the treatment groups at 2, 4, and 6 weeks. CONCLUSION PTB is as effective as standard sutures for wound closure in porcine skin in terms of cosmetic outcomes and safety.
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Affiliation(s)
- Yoko Kamegaya
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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Savage HE, Halder RK, Kartazayeu U, Rosen RB, Gayen T, McCormick SA, Patel NS, Katz A, Perry HD, Paul M, Alfano RR. NIR laser tissue welding of in vitro porcine cornea and sclera tissue. Lasers Surg Med 2004; 35:293-303. [PMID: 15493021 DOI: 10.1002/lsm.20094] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND OBJECTIVE The objective of this study was to test the hypothesis that an near infrared (NIR) laser system (1,455 nm) in combination with a motorized translational stage to control the position and speed of the laser beam and a shutter to control the laser exposure to the tissue being welded could be used to successfully weld ocular tissues. STUDY DESIGN/MATERIALS AND METHODS Seventy-five porcine corneas and 23 porcine scleral tissues were welded in vitro in this study. The welded tissues were examined using histopathology and tensile strength analysis. Eight different welding conditions were analyzed for porcine cornea and one for sclera tissues. The tensile strength of the welded groups was compared to a sutured cornea control group. RESULTS The NIR laser welding system provides strong, full thickness welds and does not require the use of extrinsic dyes, chromophores, or solders. Mean weld strengths of 0.15-0.45 kg/cm(2) were obtained for the cornea and 1.01 kg/cm(2) for sclera welds. The native H(2)O in the ocular tissue serves as an absorber of the 1,455 nm radiation and helps to induce the welds. CONCLUSIONS We conclude that an NIR laser system using an optimal laser radiation wavelength of 1,455 nm can effectively weld cornea and sclera tissue and that this laser tissue welding (LTW) methodology typically causes minimal disruption of tissue, and thus, avoids opacities and irregularities in the tissue which may result in decreased visual acuity. The optimization of a laser welding system that leads to a strong full thickness tissue bond without tissue destruction, an instant seal that promotes wound healing, and the absence of a continued presence of a foreign substance like a suture, is of considerable importance to the ophthalmology medical community. This need is especially apparent with respect to corneal transplantation and fixing the position of corneal flaps in Laser-Assisted In Situ Keratomileusis (LASIK), a laser procedure used to permanently change the shape of the cornea.
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Affiliation(s)
- Howard E Savage
- Department of Pathology, New York Eye and Ear Infirmary, 2nd Avenue & 14th Street, New York, NY 10003, USA.
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Laser literature watch. Photomed Laser Surg 2004; 22:261-76. [PMID: 15315736 DOI: 10.1089/1549541041438588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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