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Lassi Pekka Yrjänä Rieppo, Ph.D.

FT-IR spectroscopy and spectroscopic imaging

Personal information

  • Phone: +358 50 3759310
  • Room: Me/331
  • Email: lassi.rieppo [at] (please fix the address before mailing!)

  • Date of birth: 8 May 1985

  • Current research interests: FT-IR spectroscopy and spectroscopic imaging, multivariate analysis

  • Education:
    • Ph.D., Applied Physics, University of Eastern Finland, 2013
    • M.Sc., Medical Physics, University of Eastern Finland, 2010
    • B.Sc., Medical Physics, University of Eastern Finland, 2010
    • Graduate of Finnish Secondary School, Lapinlahden lukio, 2004

  • Language proficiency:
    • Finnish, native language
    • English, fluent
    • Swedish, fairly good

  • Skills: Analysis of spectroscopic data. Programming languages: Matlab, Java, HTML, PHP

  • Hobbies: Sports, music


(full papers, conference proceedings)
  1. Rieppo L, ORCID:, Janssen L, ORCID:, Rahunen K, Lehenkari P, Finnila MAJ and Saarakkala S. Histochemical quantification of collagen content in articular cartilage. PLoS One. 2019 Nov 7;14(11):e0224839. doi: 10.1371/journal.pone.0224839.

  2. Sarin JK, ORCID: 0000-0002-6237-9015, Torniainen J, ORCID: 0000-0003-4953-4508, Prakash M, Rieppo L, Afara IO, ORCID: 0000-0001-7114-0439 and Toyras J. Dataset on equine cartilage near infrared spectra, composition, and functional properties. Sci Data. 2019 Aug 30;6(1):164. doi: 10.1038/s41597-019-0170-y.

  3. Mancini IAD, Rieppo L, Pouran B, Afara IO, Braganca FMS, van Rijen MHP, Kik M, Weinans H, Toyras J, van Weeren PR and Malda J. Effects of body mass on microstructural features of the osteochondral unit: A comparative analysis of 37 mammalian species. Bone. 2019 Oct;127:664-673. doi: 10.1016/j.bone.2019.07.001. Epub 2019 Jul 3.

  4. Prakash M, Joukainen A, Torniainen J, Honkanen MKM, Rieppo L, Afara IO, Kroger H, Toyras J and Sarin JK. Near-infrared spectroscopy enables quantitative evaluation of human cartilage biomechanical properties during arthroscopy. Osteoarthritis Cartilage. 2019 Aug;27(8):1235-1243. doi:

  5. Prittinen J, Ylarinne J, Piltti J, Karhula SS, Rieppo L, Ojanen SP, Korhonen RK, Saarakkala S, Lammi MJ and Qu C. Effect of centrifugal force on the development of articular neocartilage with bovine primary chondrocytes. Cell Tissue Res. 2019 Mar;375(3):629-639. doi: 10.1007/s00441-018-2938-3. Epub

  6. Kauppinen S, Karhula SS, Thevenot J, Ylitalo T, Rieppo L, Kestila I, Haapea M, Hadjab I, Finnila MA, Quenneville E, Garon M, Gahunia HK, Pritzker KPH, Buschmann MD, Saarakkala S and Nieminen HJ. 3D morphometric analysis of calcified cartilage properties using micro-computed tomography. Osteoarthritis Cartilage. 2019 Jan;27(1):172-180. doi:

  7. Oinas J, Ronkainen AP, Rieppo L, Finnila MAJ, ORCID: 0000-0002-3348-5759, Iivarinen JT, van Weeren PR, Helminen HJ, Brama PAJ, Korhonen RK and Saarakkala S. Composition, structure and tensile biomechanical properties of equine articular cartilage during growth and maturation. Sci Rep. 2018 Jul 27;8(1):11357. doi: 10.1038/s41598-018-29655-5.

  8. Kestila I, Thevenot J, Finnila MA, Karhula SS, Hadjab I, Kauppinen S, Garon M, Quenneville E, Haapea M, Rieppo L, Pritzker KP, Buschmann MD, Nieminen HJ and Saarakkala S. In vitro method for 3D morphometry of human articular cartilage chondrons based on micro-computed tomography. Osteoarthritis Cartilage. 2018 Aug;26(8):1118-1126. doi:

  9. Nykanen O, ORCID: 0000-0001-7329-3463, Rieppo L, Toyras J, Kolehmainen V, Saarakkala S, Shmueli K, ORCID: 0000-0001-7520-2975, Nissi MJ and ORCID: 0000-0002-5678-0689. Quantitative susceptibility mapping of articular cartilage: Ex vivo findings at multiple orientations and following different degradation treatments. Magn Reson Med. 2018 Dec;80(6):2702-2716. doi: 10.1002/mrm.27216. Epub 2018 Apr

  10. Salonius E, ORCID:, Rieppo L, Nissi MJ, Pulkkinen HJ, Brommer H, Brunott A, Silvast TS, Van Weeren PR, Muhonen V, Brama PAJ and Kiviranta I. Critical-sized cartilage defects in the equine carpus. Connect Tissue Res. 2019 Mar;60(2):95-106. doi: 10.1080/03008207.2018.1455670.

  11. Gorissen BMC, ORCID:, Wolschrijn CF, van Rietbergen B, Rieppo L, Saarakkala S and van Weeren PR. Trabecular and subchondral bone development of the talus and distal tibia from foal to adult in the warmblood horse. Anat Histol Embryol. 2018 Jun;47(3):206-215. doi: 10.1111/ahe.12341. Epub 2018

  12. Pitkanen O, Jarvinen T, Cheng H, Lorite GS, Dombovari A, Rieppo L, Talapatra S, Duong HM, ORCID: 0000-0002-5667-5416, Toth G, ORCID: 0000-0003-0066-9823, Juhasz KL, Konya Z, ORCID: 0000-0002-9406-8596, Kukovecz A, Ajayan PM, Vajtai R, ORCID: 0000-0002-3942-8827 and Kordas K. On-chip integrated vertically aligned carbon nanotube based super- and pseudocapacitors. Sci Rep. 2017 Nov 29;7(1):16594. doi: 10.1038/s41598-017-16604-x.

  13. Durga Devi T, Babu M, Makinen P, Kaikkonen MU, Heinaniemi M, Laakso H, Yla-Herttuala E, Rieppo L, Liimatainen T, Naumenko N, Tavi P and Yla-Herttuala S. Aggravated Postinfarct Heart Failure in Type 2 Diabetes Is Associated with Impaired Mitophagy and Exaggerated Inflammasome Activation. Am J Pathol. 2017 Dec;187(12):2659-2673. doi: 10.1016/j.ajpath.2017.08.023. Epub

  14. Sarin JK, ORCID:, Rieppo L, Brommer H, Afara IO, ORCID:, Saarakkala S and Toyras J. Combination of optical coherence tomography and near infrared spectroscopy enhances determination of articular cartilage composition and structure. Sci Rep. 2017 Sep 6;7(1):10586. doi: 10.1038/s41598-017-10973-z.

  15. Hanninen N, ORCID: 0000-0003-0392-8552, Rautiainen J, Rieppo L, Saarakkala S and Nissi MJ. Orientation anisotropy of quantitative MRI relaxation parameters in ordered tissue. Sci Rep. 2017 Aug 29;7(1):9606. doi: 10.1038/s41598-017-10053-2.

  16. Prakash M, Sarin JK, Rieppo L, Afara IO and Toyras J. Optimal Regression Method for Near-Infrared Spectroscopic Evaluation of Articular Cartilage. Appl Spectrosc. 2017 Oct;71(10):2253-2262. doi: 10.1177/0003702817726766. Epub

  17. Han SK, Ronkainen AP, Saarakkala S, Rieppo L, ORCID: 0000-0001-5542-4060, Herzog W and Korhonen RK. Alterations in structural macromolecules and chondrocyte deformations in lapine retropatellar cartilage 9 weeks after anterior cruciate ligament transection. J Orthop Res. 2018 Jan;36(1):342-350. doi: 10.1002/jor.23650. Epub 2017 Jul 31.

  18. Viren T, Honkanen JT, Danso EK, Rieppo L, Korhonen RK and Toyras J. Ultrasound Assessment of Human Meniscus. Ultrasound Med Biol. 2017 Sep;43(9):1753-1763. doi:

  19. Nieminen HJ, Gahunia HK, Pritzker KPH, Ylitalo T, Rieppo L, Karhula SS, Lehenkari P, Haeggstrom E and Saarakkala S. 3D histopathological grading of osteochondral tissue using contrast-enhanced micro-computed tomography. Osteoarthritis Cartilage. 2017 Oct;25(10):1680-1689. doi:

  20. Rossler E, Mattea C, Saarakkala S, Lehenkari P, Finnila M, Rieppo L, Karhula S, Nieminen MT, Stapf S and ORCID: Correlations of low-field NMR and variable-field NMR parameters with osteoarthritis in human articular cartilage under load. NMR Biomed. 2017 Aug;30(8). doi: 10.1002/nbm.3738. Epub 2017 May 24.

  21. Rieppo L, Kokkonen HT, Kulmala KA, Kovanen V, Lammi MJ, Toyras J and Saarakkala S. Infrared microspectroscopic determination of collagen cross-links in articular cartilage. J Biomed Opt. 2017 Mar 1;22(3):35007. doi: 10.1117/1.JBO.22.3.035007.

  22. Karhula SS, Finnila MA, Lammi MJ, Ylarinne JH, Kauppinen S, Rieppo L, Pritzker KP, Nieminen HJ and Saarakkala S. Effects of Articular Cartilage Constituents on Phosphotungstic Acid Enhanced Micro-Computed Tomography. PLoS One. 2017 Jan 30;12(1):e0171075. doi: 10.1371/journal.pone.0171075.

  23. Oinas J, Rieppo L, Finnila MA, Valkealahti M, Lehenkari P and Saarakkala S. Imaging of Osteoarthritic Human Articular Cartilage using Fourier Transform Infrared Microspectroscopy Combined with Multivariate and Univariate Analysis. Sci Rep. 2016 Jul 21;6:30008. doi: 10.1038/srep30008.

  24. Mikkonen JJ, Raittila J, Rieppo L, Lappalainen R, Kullaa AM and Myllymaa S. Fourier Transform Infrared Spectroscopy and Photoacoustic Spectroscopy for Saliva Analysis. Appl Spectrosc. 2016 Sep;70(9):1502-10. doi: 10.1177/0003702816654149. Epub 2016

  25. Rieppo L, Saarakkala S, Jurvelin JS and Rieppo J. Optimal variable selection for Fourier transform infrared spectroscopic analysis of articular cartilage composition. J Biomed Opt. 2014 Feb;19(2):027003. doi: 10.1117/1.JBO.19.2.027003.

  26. Rieppo L, Narhi T, Helminen HJ, Jurvelin JS, Saarakkala S and Rieppo J. Infrared spectroscopic analysis of human and bovine articular cartilage proteoglycans using carbohydrate peak or its second derivative. J Biomed Opt. 2013 Sep;18(9):097006. doi: 10.1117/1.JBO.18.9.097006.

  27. Rieppo L, Saarakkala S, Jurvelin JS and Rieppo J. Prediction of compressive stiffness of articular cartilage using Fourier transform infrared spectroscopy. J Biomech. 2013 Apr 26;46(7):1269-75. doi: 10.1016/j.jbiomech.2013.02.022. Epub

  28. Kobrina Y, Rieppo L, Saarakkala S, Pulkkinen HJ, Tiitu V, Valonen P, Kiviranta I, Jurvelin JS and Isaksson H. Cluster analysis of infrared spectra can differentiate intact and repaired articular cartilage. Osteoarthritis Cartilage. 2013 Mar;21(3):462-9. doi: 10.1016/j.joca.2012.12.005.

  29. Pulkkinen HJ, Tiitu V, Valonen P, Jurvelin JS, Rieppo L, Toyras J, Silvast TS, Lammi MJ and Kiviranta I. Repair of osteochondral defects with recombinant human type II collagen gel and autologous chondrocytes in rabbit. Osteoarthritis Cartilage. 2013 Mar;21(3):481-90. doi: 10.1016/j.joca.2012.12.004.

  30. Kulmala KA, Pulkkinen HJ, Rieppo L, Tiitu V, Kiviranta I, Brunott A, Brommer H, van Weeren R, Brama PA, Mikkola MT, Korhonen RK, Jurvelin JS and Toyras J. Contrast-Enhanced Micro-Computed Tomography in Evaluation of Spontaneous Repair of Equine Cartilage. Cartilage. 2012 Jul;3(3):235-44. doi: 10.1177/1947603511424173.

  31. Rieppo L, Rieppo J, Jurvelin JS and Saarakkala S. Fourier transform infrared spectroscopic imaging and multivariate regression for prediction of proteoglycan content of articular cartilage. PLoS One. 2012;7(2):e32344. doi: 10.1371/journal.pone.0032344. Epub 2012 Feb 16.

  32. Kobrina Y, Rieppo L, Saarakkala S, Jurvelin JS and Isaksson H. Clustering of infrared spectra reveals histological zones in intact articular cartilage. Osteoarthritis Cartilage. 2012 May;20(5):460-8. doi: 10.1016/j.joca.2012.01.014.

  33. Rieppo L, Saarakkala S, Narhi T, Helminen HJ, Jurvelin JS and Rieppo J. Application of second derivative spectroscopy for increasing molecular specificity of Fourier transform infrared spectroscopic imaging of articular cartilage. Osteoarthritis Cartilage. 2012 May;20(5):451-9. doi: 10.1016/j.joca.2012.01.010.

  34. Kokkonen HT, Makela J, Kulmala KA, Rieppo L, Jurvelin JS, Tiitu V, Karjalainen HM, Korhonen RK, Kovanen V and Toyras J. Computed tomography detects changes in contrast agent diffusion after collagen cross-linking typical to natural aging of articular cartilage. Osteoarthritis Cartilage. 2011 Oct;19(10):1190-8. doi:

  35. Turunen MJ, Saarakkala S, Rieppo L, Helminen HJ, Jurvelin JS and Isaksson H. Comparison between infrared and Raman spectroscopic analysis of maturing rabbit cortical bone. Appl Spectrosc. 2011 Jun;65(6):595-603. doi: 10.1366/10-06193.

  36. Sierra A, Laitinen T, Lehtimaki K, Rieppo L, Pitkanen A and Grohn O. Diffusion tensor MRI with tract-based spatial statistics and histology reveals undiscovered lesioned areas in kainate model of epilepsy in rat. Brain Struct Funct. 2011 Jun;216(2):123-35. doi: 10.1007/s00429-010-0299-0. Epub

  37. Kobrina Y, Isaksson H, Sinisaari M, Rieppo L, Brama PA, van Weeren R, Helminen HJ, Jurvelin JS and Saarakkala S. Infrared spectroscopy reveals both qualitative and quantitative differences in equine subchondral bone during maturation. J Biomed Opt. 2010 Nov-Dec;15(6):067003. doi: 10.1117/1.3512177.

  38. Julkunen P, Halmesmaki EP, Iivarinen J, Rieppo L, Narhi T, Marjanen J, Rieppo J, Arokoski J, Brama PA, Jurvelin JS and Helminen HJ. Effects of growth and exercise on composition, structural maturation and appearance of osteoarthritis in articular cartilage of hamsters. J Anat. 2010 Sep;217(3):262-74. doi: 10.1111/j.1469-7580.2010.01270.x. Epub 2010

  39. Isaksson H, Turunen MJ, Rieppo L, Saarakkala S, Tamminen IS, Rieppo J, Kroger H and Jurvelin JS. Infrared spectroscopy indicates altered bone turnover and remodeling activity in renal osteodystrophy. J Bone Miner Res. 2010 Jun;25(6):1360-6. doi: 10.1002/jbmr.10.

  40. Rieppo L, Saarakkala S, Narhi T, Holopainen J, Lammi M, Helminen HJ, Jurvelin JS and Rieppo J. Quantitative analysis of spatial proteoglycan content in articular cartilage with Fourier transform infrared imaging spectroscopy: Critical evaluation of analysis methods and specificity of the parameters. Microsc Res Tech. 2010 May;73(5):503-12. doi: 10.1002/jemt.20789.

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