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Porphyrins as theranostic agents from prehistoric to modern times.

Zhang Y, Lovell JF - Theranostics (2012)

Bottom Line: Long before humans roamed the planet, porphyrins in blood were serving not only as indispensable oxygen carriers, but also as the bright red contrast agent that unmistakably indicates injury sites.Exogenous porphyrins remain in clinical use for photodynamic therapy.Going forward, intrinsic porphyrin biocompatibility and multimodality will keep new applications of this class of molecules at the forefront of theranostic research.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Chemical and Biological Engineering;

ABSTRACT
Long before humans roamed the planet, porphyrins in blood were serving not only as indispensable oxygen carriers, but also as the bright red contrast agent that unmistakably indicates injury sites. They have proven valuable as whole body imaging modalities have emerged, with endogenous hemoglobin porphyrins being used for new approaches such as functional magnetic resonance imaging and photoacoustic imaging. With the capability for both near infrared fluorescence imaging and phototherapy, porphyrins were the first exogenous agents that were employed with intrinsic multimodal theranostic character. Porphyrins have been used as tumor-specific diagnostic fluorescence imaging agents since 1924, as positron emission agents since 1951, and as magnetic resonance (MR) contrast agents since 1987. Exogenous porphyrins remain in clinical use for photodynamic therapy. Because they can chelate a wide range of metals, exogenous porphyrins have demonstrated potential for use in radiotherapy and multimodal imaging modalities. Going forward, intrinsic porphyrin biocompatibility and multimodality will keep new applications of this class of molecules at the forefront of theranostic research.

No MeSH data available.


Related in: MedlinePlus

Endogenous porphyrins. a) Schematic organization of heme in the body 6,9. b) A possible heme-containing red blood cell identified in 65 million year old dinosaur tissue 7. c) Surgical illustration of an amputation from circa 1500 AD. Excessive bleeding can readily be observed due to the bright red heme to guide tourniquet application (Archives & Special Collections, Columbia University Health Sciences Library). d) BOLD MR imaging using heme oxygenation. In this case neural differences between English and Hebrew speech patterns are shown. Blue and red regions are involved in morphological processing in Hebrew and English, respectively and regions of overlap are shown in purple 22. e) Non-invasive, rat brain transcranial photoacoustic imaging following right-side whisker stimulation 26. Reproduced with permission from the publishers of corresponding references.
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Figure 1: Endogenous porphyrins. a) Schematic organization of heme in the body 6,9. b) A possible heme-containing red blood cell identified in 65 million year old dinosaur tissue 7. c) Surgical illustration of an amputation from circa 1500 AD. Excessive bleeding can readily be observed due to the bright red heme to guide tourniquet application (Archives & Special Collections, Columbia University Health Sciences Library). d) BOLD MR imaging using heme oxygenation. In this case neural differences between English and Hebrew speech patterns are shown. Blue and red regions are involved in morphological processing in Hebrew and English, respectively and regions of overlap are shown in purple 22. e) Non-invasive, rat brain transcranial photoacoustic imaging following right-side whisker stimulation 26. Reproduced with permission from the publishers of corresponding references.

Mentions: Porphyrins exist abundantly in plants, animals and rocks 1 and have even been found in lunar dust 2. They existed by the time the first chlorophyll-containing photosynthetic organisms appeared some 3 billion years ago to initiate the creation of a new atmosphere, rich with life-supporting oxygen 3. Our present ecosystem relies extensively on porphyrins for various vital roles ranging from photosynthesis to oxygen transport, in the form of chlorophyll and heme. Iron, which is chelated in the center of the heme group, may have been selected instead of another metal for evolutionary reasons, due to its abundance in the crust of earth 4. Hemoglobin and myoglobin are believed to have emerged more than 600 million years ago 5. Structurally, hemoglobin consists of four protein subunits, with each subunit associated with a heme group chelated with an iron atom in the center (Fig 1a) 6. Its evolution permitted animals to develop complex circulatory systems, which in turn permitted larger organism sizes and higher functions. Hemoglobin is packed into red blood cells (RBCs), which are the most abundant cells in blood and can be traced back to ancient times (for e.g., a probable 65 million year old dinosaur RBC is shown in Fig. 1b) 7. RBCs have a characteristic biconcave shape 7-8 µm in diameter and play a major role in human physiology 8. RBCs are produced at an astounding rate of approximately 2×106 per second and there are 2-3×1013 in circulation at any given moment in a human adult body. Oxygen delivery is mediated by the nearly 300 million hemoglobin molecules in each RBC, which comprise some 3 x 1022 total heme porphyrin group in the body 9 (Fig 1a). In addition, a wide range of other porphyrins is found in prosthetic groups within cells (e.g. cytochromes and vitamin B12).


Porphyrins as theranostic agents from prehistoric to modern times.

Zhang Y, Lovell JF - Theranostics (2012)

Endogenous porphyrins. a) Schematic organization of heme in the body 6,9. b) A possible heme-containing red blood cell identified in 65 million year old dinosaur tissue 7. c) Surgical illustration of an amputation from circa 1500 AD. Excessive bleeding can readily be observed due to the bright red heme to guide tourniquet application (Archives & Special Collections, Columbia University Health Sciences Library). d) BOLD MR imaging using heme oxygenation. In this case neural differences between English and Hebrew speech patterns are shown. Blue and red regions are involved in morphological processing in Hebrew and English, respectively and regions of overlap are shown in purple 22. e) Non-invasive, rat brain transcranial photoacoustic imaging following right-side whisker stimulation 26. Reproduced with permission from the publishers of corresponding references.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3475213&req=5

Figure 1: Endogenous porphyrins. a) Schematic organization of heme in the body 6,9. b) A possible heme-containing red blood cell identified in 65 million year old dinosaur tissue 7. c) Surgical illustration of an amputation from circa 1500 AD. Excessive bleeding can readily be observed due to the bright red heme to guide tourniquet application (Archives & Special Collections, Columbia University Health Sciences Library). d) BOLD MR imaging using heme oxygenation. In this case neural differences between English and Hebrew speech patterns are shown. Blue and red regions are involved in morphological processing in Hebrew and English, respectively and regions of overlap are shown in purple 22. e) Non-invasive, rat brain transcranial photoacoustic imaging following right-side whisker stimulation 26. Reproduced with permission from the publishers of corresponding references.
Mentions: Porphyrins exist abundantly in plants, animals and rocks 1 and have even been found in lunar dust 2. They existed by the time the first chlorophyll-containing photosynthetic organisms appeared some 3 billion years ago to initiate the creation of a new atmosphere, rich with life-supporting oxygen 3. Our present ecosystem relies extensively on porphyrins for various vital roles ranging from photosynthesis to oxygen transport, in the form of chlorophyll and heme. Iron, which is chelated in the center of the heme group, may have been selected instead of another metal for evolutionary reasons, due to its abundance in the crust of earth 4. Hemoglobin and myoglobin are believed to have emerged more than 600 million years ago 5. Structurally, hemoglobin consists of four protein subunits, with each subunit associated with a heme group chelated with an iron atom in the center (Fig 1a) 6. Its evolution permitted animals to develop complex circulatory systems, which in turn permitted larger organism sizes and higher functions. Hemoglobin is packed into red blood cells (RBCs), which are the most abundant cells in blood and can be traced back to ancient times (for e.g., a probable 65 million year old dinosaur RBC is shown in Fig. 1b) 7. RBCs have a characteristic biconcave shape 7-8 µm in diameter and play a major role in human physiology 8. RBCs are produced at an astounding rate of approximately 2×106 per second and there are 2-3×1013 in circulation at any given moment in a human adult body. Oxygen delivery is mediated by the nearly 300 million hemoglobin molecules in each RBC, which comprise some 3 x 1022 total heme porphyrin group in the body 9 (Fig 1a). In addition, a wide range of other porphyrins is found in prosthetic groups within cells (e.g. cytochromes and vitamin B12).

Bottom Line: Long before humans roamed the planet, porphyrins in blood were serving not only as indispensable oxygen carriers, but also as the bright red contrast agent that unmistakably indicates injury sites.Exogenous porphyrins remain in clinical use for photodynamic therapy.Going forward, intrinsic porphyrin biocompatibility and multimodality will keep new applications of this class of molecules at the forefront of theranostic research.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Chemical and Biological Engineering;

ABSTRACT
Long before humans roamed the planet, porphyrins in blood were serving not only as indispensable oxygen carriers, but also as the bright red contrast agent that unmistakably indicates injury sites. They have proven valuable as whole body imaging modalities have emerged, with endogenous hemoglobin porphyrins being used for new approaches such as functional magnetic resonance imaging and photoacoustic imaging. With the capability for both near infrared fluorescence imaging and phototherapy, porphyrins were the first exogenous agents that were employed with intrinsic multimodal theranostic character. Porphyrins have been used as tumor-specific diagnostic fluorescence imaging agents since 1924, as positron emission agents since 1951, and as magnetic resonance (MR) contrast agents since 1987. Exogenous porphyrins remain in clinical use for photodynamic therapy. Because they can chelate a wide range of metals, exogenous porphyrins have demonstrated potential for use in radiotherapy and multimodal imaging modalities. Going forward, intrinsic porphyrin biocompatibility and multimodality will keep new applications of this class of molecules at the forefront of theranostic research.

No MeSH data available.


Related in: MedlinePlus