peri = around, vascular = vessels

perivascular means around blood vessels.

pericytes and mesenchymal stem/stromal cells (possible the same thing but probably pericytes are a precursor to MSCs) localise around blood vessels and regulate many things in response to injury. for example, MSCs reduce inflammation and stimulate repair mostly by paracrine mechanisms, they regulate immune cell activity and regulate angiogenesis. with these functions in mind, it may not be surprising that they play a role in tumours which require a blood supply, activate an immune response and cause local injury. Dissemination typically involves tumour cells entering the vasculature, again linking to regulation by the 'perivascular niche'.

The HSC niche is not the same as this refers to the bone marrow. MSCs are major contributors to this niche in regulating HSCs and vice versa. So, the HSC niche may be considered as a specific specialised pervascular niche.

Your whole body has blood vessels so the perivascular niche is also throughout your body. Therefore it is always involved in tumour. Tumours are also likely to form in precursor/stem cells as these cell types already have self-renewal capacity. Then, as I said, MSCs are highly involved in regulating local microenvironment and stem cell regulation so if it is not the perivascular stem cells that have formed the tumous, they are somewhere very nearby.

Hi Hyun

Perivasucular niche means that tumor cell bind to vascular vessel and locate in "Y" shape (out side of vessel). Please see Nat Cell Biol's paper carefully. MDA-MB-231 cell associates with vascular vessel in any organs (not only bone marrow).

Recently, it is reported that cancer stem cell-like cell also locate in same place.

HSC' niche is special place and needs stromal cell. 

Figure 7 in Nat Cell Biol's paper is very important to understand "perivascular niche".

Thanks for your answer Mr. Hisashi. Could you give me the reference article " cancer stem cell-like cell also locate in same place"?  My second question is that if vascular vessel is the key that consists perivascular niche, then is it possible to build a in vitro vascular niche model composed only of endothelial cells, excluding stromal cells? Thanks in advance.

In Nat Cell Biol's paper, they said "dormant cells". It is similar to cancer stem cells.

Please see attached paper.

2nd, to make a perivascular niche needs mural cells (pericyte, smooth muscle)

and other tissue stromal cells (not bone marrow's stream cells).

These complex make a "perivascular niche". 

Actually, some group including Dr. Kyoto Hida can use tumor endothelial cells. 

(But its is very difficult to do your suggested experiment)

peri = around, vascular = vessels

perivascular means around blood vessels.

pericytes and mesenchymal stem/stromal cells (possible the same thing but probably pericytes are a precursor to MSCs) localise around blood vessels and regulate many things in response to injury. for example, MSCs reduce inflammation and stimulate repair mostly by paracrine mechanisms, they regulate immune cell activity and regulate angiogenesis. with these functions in mind, it may not be surprising that they play a role in tumours which require a blood supply, activate an immune response and cause local injury. Dissemination typically involves tumour cells entering the vasculature, again linking to regulation by the 'perivascular niche'.

The HSC niche is not the same as this refers to the bone marrow. MSCs are major contributors to this niche in regulating HSCs and vice versa. So, the HSC niche may be considered as a specific specialised pervascular niche.

Your whole body has blood vessels so the perivascular niche is also throughout your body. Therefore it is always involved in tumour. Tumours are also likely to form in precursor/stem cells as these cell types already have self-renewal capacity. Then, as I said, MSCs are highly involved in regulating local microenvironment and stem cell regulation so if it is not the perivascular stem cells that have formed the tumous, they are somewhere very nearby.

Thank you Mr. Sweeney.

What I've understood is this: perivascular niche can be found anywhere a blood vessel exists. And the HSC niche is a HSC-specific version of perivascular niche in BM. 

If my understanding is correct, I have one more question, which is closely related to my thesis. Angiopoietin-1 (Ang-1) is present both in BM HSC niche and perivascular niche. And as I've cited, prostate cancer (PCa) cells reside in BM HSC niche, Breast cancer (BCa) cells reside in perivascular niche. My hypothesis is this: Ang-1 may act on the disseminated PCa and BCa cells, inhibiting both proliferation and apoptosis, as it does to the ECs and the HSCs. I think if it does then it can add explanations to the mechanism of tumor dormancy. Though I've been working on this thesis a couple of years, all these terms are so confusing. Do you have any suggestions to build-up this theory? Or is it a concept that is already familiar in this field?

Hello

I a greed with researchers . also Please see the study ( Tamplin OJ ) , Which showed that endothelial cells surround a single HSPC attached to a single mesenchymal stromal cell. and ability to reconstitute and sustain the entire blood system . also, revealed interactions between single HSPCs and their niche. When an HSPC arrives in the perivascular niche, a group of endothelial cells remodel to form a surrounding pocket. This structure appears conserved in mouse fetal liver. Correlative light and electron microscopy revealed that endothelial cells surround a single HSPC attached to a single mesenchymal stromal cell. Live imaging showed that mesenchymal stromal cells anchor HSPCs and orient their divisions. A chemical genetic screen found that the compound lycorine promotes HSPC-niche interactions during development and ultimately expands the stem cell pool into adulthood.

Good luck

http://www.ncbi.nlm.nih.gov/pubmed/25594182